Yes I was thinking it may be underpowered for what I generally do amiga wise, which is old games and some creative things.
No experience with MOS myself, but I will say that Power Mac G4s are easily had for very affordable prices and are by far the most expandable G4 machines. If you're not planning to use it for OS9, I'd just go ahead and nab a
refurbished 1.25GHz MDD model from GainSaver - they're cheap because it's only single-CPU, but IIRC MOS can't use dual anyway, right? Max it out with 2GB DDR233 and a nice sizable IDE disk and you're set, it even comes with a Radeon 9000 Pro - not the
creme de la creme, but certainly enough for a good starting point.
Also, in regards to the OP and comparing PPC/x86, my PowerBook G4 @ 1.33GHz benches just behind my Eee (Atom N270) @ 1.6GHz (and would probably equal it if it had DDR2,) and actually surpasses it in a variety of applications in practical use. For whatever that's worth.