There's no way to know exactly how many Power Macs are still out there. A conservative estimate probably puts the worldwide count somewhere in the low hundred thousands for active use, maybe shy of a million in some sort of infrequent operation and innumerable more in closets and storage, but this is all just supposition. Some get only occasional use, I'm quite sure some don't use TenFourFox, and of those that do they may only run it periodically. Furthermore, some may dual boot Linux or *BSD, some might be in Mac OS 9 most of the time now, and some might not even be running Mac OS of any sort anymore. We just know that you're out there, somewhere.
The total TenFourFox userbase must be less than 18,000 machines or so, based on the average number of downloads per version, though the actual number is likely in that ballpark. Google Code has tracked our download numbers over time under the Downloads tab and the number has declined a bit from the days of TenFourFox 4, but is still a surprisingly large number of machines and relatively stable. This number, by the way, is totally organic and grown by word of mouth; we don't advertise anywhere, so it's really gratifying to see these kinds of stats for what is essentially a hobby project. Of these, a minority check in with the update server daily, approximately 4,000, more on weekdays and slightly fewer on weekends. This is an approximation, because I can't actually identify or track individual machines, but a stable one.
This population of machines that checks in daily is, serendipitously, the most interesting group to study. Since checkins only happen daily if the Mac is on and the browser is running, these are likely to be people using a Power Mac regularly for their normal tasks, so let's take a closer look at the data. What might a daily Power Mac user look like 7 years after the switch?
First, some methodology: only fully valid, "legible" checkins were used; a handful of checkins demonstrated activity like TenFourFox would, but had obscured or obviously bogus user agent strings, so they were dropped. Builds tagged as "Debugging" were also dropped if they checked in, since they are not release builds by definition. The numbers are a composite of several days averaged out, so take them as merely representative and not exact. I expect that machines may drop in and out from day to day; thus, the numbers observed may not necessarily be the same machines each day, even though the numbers are broadly similar. Okay, enough fine print. Here we go.
First, here's the breakdown by operating system. The operating system is directly checked by TenFourFox and reported, unless it was overridden by a user-agent tool, so it is fairly reliable. No surprises that 10.5 is the majority, but 10.4 maintains a very strong percentage. (Note that since 10.3 and prior cannot run TenFourFox, we don't track it. There is probably a non-trivial number of machines in that category. Classilla does not have automatic checkins, so I can't say anything about OS 9 here.) Interestingly, a very small sliver of 10.6 users was detected, around two or three a day, despite the fact that Firefox (at least for the moment) still runs natively on Snow Leopard. On one notable outlier day, we picked up eight of them.
Now the breakdown by CPU. While we could write code to detect the CPU at runtime, TenFourFox doesn't use it so that build automation is less complex; instead, this number comes from the build that the user chose to download, so these numbers are a bit less reliable (more below). The top two are no surprise: G4/7450, not only because of the Power Mac G4 but the large number of PowerBook G4s, and of course the G5. G4/7400 and G3 builds represent less than 10% of the daily checkins combined, though they equal around 20% of the total downloads, suggesting these machines are not usually daily drivers. A sliver of "386" (Intel) users still rock the presently stalled experimental Intel build.
Combining the two is where it starts getting interesting. I've harmonized the colours in iWork and exploded out the slices so that you can visually compare this image to the prior one. Most G5 users prefer 10.5 by over 2 to 1, and this is pretty much as expected given that the G5 seems to perform better in 10.5 than 10.4; it's the logical choice for G5 users if you don't need 10.4 for compatibility. (I do, though, so Tiger forever.) For G4/7450 users, however, 10.4 has a slight edge over 10.5, likely because lower specification machines don't do as well in Leopard.
Unfortunately, our numbers get hosed a bit in the minority slices because of builds running on an obviously different host architecture. The 7400 users on 10.5 are probably real, since the OpenFirmware hack to get the installer working is well-known, but most G4/7400 users are on 10.4 as expected (as are almost all the G3 owners). The 10.6 users must be using a PPC build of some sort under Rosetta, so there's not a whole lot more that can reliably be said about them. The so-called "G3 + 10.5" users, on the other hand, are bogus without a doubt; these might be Intel users, since we advertise the G3 build specifically for Intel under Rosetta in the FAQ. Most of the true Intel build users are on 10.4, which is bad news for issue 209.
While Power Mac users may not be up with the latest and (if Apple marketing is to be believed) greatest new hardware, the TenFourFox userbase is pretty good at upgrading. Roughly three-quarters of the active users are on 17.0.x, the current stable major version, and over half of those are on 17.0.7, the most current release in that series. (The number plunges to around 500 for the immediately preceding version 17.0.6 and rapidly falls off from there.) Add the four percent of users on 22, and almost 80% of our user base is on a supported branch of some sort. From this, developers should confidently infer that most active Power Mac users would gladly update their software if you offered. You should offer. I'm just saying.
The biggest chunk of users off the wagon are still on 10.0.x, our previous stable major version, which has not been updated for almost nine months; more alarming is that 10.0.11, the last release in that branch, is not at all the majority. I have some theories about this, but they'll all be moot pretty soon. They represent around 10% of the user base.
I've also combined all of the pre-10 versions into a single slice rather than break them down into infinitesimal shards, since summed up they represent only a bit over five percent of users. These are all scattered handfuls with no one version having a clear predominance and the numbers are too small in general to make reliable hypotheses. However, there is a slightly significant correlation between our "10.6" users and versions prior to 8.0, which was when we started the transition to methodjit, implying that these folks are still relying on good old tracejit (on the other hand, those that aren't are uniformly on 17, as they should be). At least a couple users are still using a pre-4.0 beta (!). Y'all upgrade soon now, y'hear?
A similarly small fraction of our user base is using unstable branch builds (i.e., versions 11-15 and 19-22 inclusive), which is understandable, but distressing for maintaining a solid and statistically relevant beta test population. Some people are still using unstable builds as old as 11.0 (shame on you). Fortunately, most of you are current. The 22 figure includes those brave souls who dared to try the 22.1 experiment that failed, sigh.
The best news, though, is looking at the user base figures over time. Seven years after the switch, the Power Mac may be a strict minority in the Apple ecosystem, but we're still alive and well despite their best efforts to stick the shiv in. While we suffer some attrition from machines breaking down and people moving on, the user base at least from this surveyor's eye may be small but still remains constant. Heck, you can still buy used ones easily and inexpensively from resellers like PowerMax, meaning it's a great time to pick up spare gear and keep your machine humming. I think I'll probably make this an annual feature of this blog from now on just to see how we're doing in our little RISC foxhole. Here's to seven more years of getting screwed by Cupertino.