Yes my ideal Amiga would be a 1 GHz 3.9 setup to be honest. I just think that if i'm going to be breaking compatibility with my Amiga by using AROS, then I might as well just use Windows instead.
Unless Thomas and Gunnar secure a LOT more money, you're not going to see a 1 Ghz 68K (although that WOULD be pretty cool).
As much as I hate to admit it, Windows is a valid option (remember that unoffical motto - Windows X, it suck much less now!). Personally, I'd choose it over OSX. Plus, if you're going to rely on emulation, Amiga Forever is a surprisingly good package.
So why am I using a MorphOS system (when I have two copies of WinXP Media Center and one copy of Vista)?
First, really fast boot times.
Second, efficiency. MOS performs much better than OSX on PPC machines.
Third, it provides an advanced Amiga like development platform.
Fourth, its different (and I'm not supporting Gates or Jobs).
Fifth, it is a practical platform for every day use that carries forward an OS I'm very fond of.
So, the question I always like to propose to people in your position is this - have you tried an NG OS?
AROS is free and if you're going to move to Windows, well you're already getting an X86 systems - why not try it?
MorphOS can be downloaded. The Amiga/PPC accelerated version is free and the later versions can be used as a trial version (that works for 30 minutes before slowing down). I put together my original Quicksilver based system for under $75 (so when MOS 2.6 was introduced I didn't have much invested).
I was skeptical at first, but since I adopted it, I haven't used Windows (at all, for about the last two months).
To everyone, before you decide, you ought to give an NG OS a try.