Show me some ARM machine I can buy that is faster than a Powermac G5 QuadCore from 7 years ago. If there are no faster ARM machines available in the mass market then ARM is 7 years behind PPC.
Yeah, this is really the crux of the issue:
there just isn't any good ARM platform out there, not for general-purpose computing. Don't get me wrong, I'm looking forward to the Raspberry Pi and everything, but I've spent the last two years watching semiconductor manufacturers pour quadzillions of dollars into ever-better ARM cores for tablets and smartphones and screaming "
Give it to me in a laptop already!" at my screen. (And no, tablet + keyboard is not the same thing. Give me something I can put 4GB RAM and a 320GB hard drive in, damn it.) Even the couple attempts at an ARM netbook I've seen are based on old cores that don't come close to matching my old, janky P4 laptop from 2004 for horsepower, let alone my trusty Eee.
Those complains about cpus usually come from ex-amiga users or people who doesn't use amiga at all. My powerbook G4 at 1.67Ghz runs MorphOS nicely and MorphOS would fly on a 2.5-2.7Ghz G5.
Quite. My PowerBook/Linux attempt may have been abortive, but one thing I did find is that a 1.67GHz PowerBook is perfectly satisfactory for everything except streaming video; if there were one based on a newer chip with a faster FSB I can't imagine I'd have any complaints at all.