Most of the people didn't read your post very well. I agree that emulating a "PowerPC Amiga" on the PowerMac should run much faster than a classic amiga that has been upgraded with a CS or Blizzard PPC card. If nothing else bus speeds alone should make it worth while.
Heres the thing. It shouldn't be emulation as it is WinUAE but it should be emulation in same way that Fusion works on Classic Amigas or how MOL works under PPC Linux. You only emulate what is missing. There is no reason to emulate a PowerPC CPU when you have one available. Therefore the PPC emulation would be quite quick. In addition if your goal is to just have WarpUp stuff work then you keep the 68K emulation how it is, but allow the WarpUp stuff to access the PowerPC directly. There may be some timing issues and context swap speed problems when moving from 68K to PPC code but it should still be quite powerful. And it would be another one up on the windows world who wouldn't be able to take advantage of that portion of the emulation :p
There are a few problems that I forsee. One you have to somehow integrate into the UAE code the ability to have a PowerPC native CPU available which would probably range from somewhat challenging to ludicrous depending on the cleanliness of the code. Second you would need AmigaOS 4.0 to really get any 68K performance (as the 68K emulator would be running on the native PowerPC cpu).
I am sure there are millions of things I am missing but it's quite doable and I believe it to be a good idea.
