I use Carrara at home on a G4, mostly, but I also installed it on my G5 at work, so I can render big animations more quickly if I need to. I have only played with it for about 2 hours there, but it runs nicely. It's a dual processor machine, and I can see both processors running when I render (the yellow render block with the "1" in it is joined by a red one with a "2" in it). So, not a lot of time under my belt, but certainly a positive experience so far. Certainly much MUCH faster than my G4.