9.0 is now in the release channel and available to users. As stated in the previous blog entry, methodjit is not on by default for the unwashed masses, just the regex compilation with tracejit which so far has proven to be very fast and safe.
So far there have been no reported crashes with methodjit, but I have received at least two reports of significant slowdowns on selected sites. We are tracking these in issue 119. Please only report sites there that are clearly and reproducibly being degraded by methodjit (i.e., you turn off methodjit and the problem goes away; you turn methodjit back on and the site drags back down again), not general slow issues or slowness from some other cause. It would also help to isolate a script as the specific cause using NoScript or similar tools in case we have to minimize a test case.
Type inference is still being difficult, but the MIPS port does not require anything extra of significance for it to work and MIPS is "big RISC" like us, so it's clearly something I've done wrong I haven't found yet. Right now I'm investigating stub calls, since they are by design non-ABI-compliant, and the extant code may be just clever enough to get it working in some places but not others. It is also possible that these two problems may be related.
I have also made the executive decision that we will not advance to 10 until we have both type inference and the basic methodjit working with no showstopper failures (i.e., no reproducible crashes or long hangs that are not reproducible in stock Firefox, and composite benchmarks that are not significantly worse than tracejit). We will issue interim 9 releases until then, because odds are good tracejit will be in serious disrepair in 10, even though it still exists. When I have these two issues nailed out, there will be a 9.0.1pre for you loyal beta users to try.