i've been using for a few months a 2,5ghz Corei7 cpu that i overclocked at 3,8ghz, running perfectly stable and blazzing fast, and who does need more than air cooling and keeps at decent temperatures. I don't remember any PowerPC processor able of doing that without being water cooled.
Not to start a debate, but it is quite obvious that X86 is finally going to an interesting direction and PowerPC is agonising, trapped in its limits. And no one cares to work on making it evolve or progress.
The Amiga spirit was driven with innovation, pushing the limits, at least on the glory days. Now the Amiga spirit looks like something that doesn't dare. Stuck on old technologies, stuck on old hardware, stuck on its holy compability (the most efficient blocker), etc.

I would never blame someone that loves tu use vintage cars, as long as he loves driving them, but isn't computing in general about progress ?