If you can prove that Firefox's optimizations actually make incorrect results in any way, I am 100% behind whoever claims that micro optimizations are bad. However by firefox making them it means that I don't have to worry about the nitty gritty details about what order of instructions will perform better without changing the code. Or things like loop unrolling that don't have to be done in my checked in source.
Yea I think this argument is about 30 years too late...
If anything this proves FF3 is awesome.
Regarding web standards... As much as I am 100% for having good web standards, what good is adhering to a standard when no one can use it. I use the acid tests as an indication that browser x, y and z are browsers I want to be supporting. Unfortunately I always have to support IE... Sometimes even IE6, so acid tests are just nice-to-haves at this point. I just can't wait till IE7 completely dies (hopefully it won't be as long as IE6).