G5 Altivec performance is boosted by the fast memory bus. In contrast G4 memory bus chokes and causes a bottleneck.

G4 may be faster than slowest G5 but the difference is that G5 scales to almost twice the frequency: You can buy 2.8Ghz G5 with 900Mhz memory buses: that makes any G4 bite the dust and that's why people would want it.

An iMac G5 running at 2.5Ghz with Radeon 9600 gfx card would be a good MorphOS target. It would be a good platform to start developing 3D support for R9600 series too.

Those who dream about 4GB of ram better forget it: AmigaOS/MorphOS are 32bit OSes and won't use more than 2GB of ram.

[ Edited by Crumb on 2008/10/1 11:19 ]