I'm an editor using fcp and my experience of OS X across 8 or so machines (G3,G4,G5) is bad, bad, bad. These machines were mostly setup by Apple vendors, but a couple by me, and I've had more problems with this OS than anything else I've ever used. I'm sticking with OS 9.2.2, because the basics of editing were covered admirably with fcp3 and I can point to several broadcast projects I have cut with it. I find Aqua an annoying interface that gets in the way of work and is nowhere as intuitive or fast as OS 9. I wish you could turn those animations off and I hate the fact you have a mouse speed to cursor relationship that is not linear. Believe me, I'm just getting started. I used to sell Macs 5 years ago - two months ago I bought a PC for some tasks, and strangely enough it has been excellent so far. Very fast and powerful and a heck of a lot cheaper than the Mac alternative. I hate OS X.
Mac OS 7.5: Better than Tiger Will Ever Be