002R for me, I love it but question whether I need it in my current set up. Seems like I'd get by with Garageband and a USB mic most days. It's not certified to run with Leopard but I do, just some plug in issues.
I have an 003 Rack that I got in August. I have a 2005 PowerPC based Mac Mini with 1GB RAM and 80Gig Harddrive. I use this interface exclusively as I am still in school and cannot afford any outboard gear. As of right now, I only have an external 500GB harddrive to use with it and for playback, mixing, I use my old HiFi stereo as monitors. I mix "inside the box." I am considering a midi controller of some kind to help put the mixing into more physical, hands on terms. But cost couldnt be justified for the regular control version of the 003. I use OSX 10.4.11 and had a major crash with PT because my startup disk was being temperamental and didnt like Quicktime 7. so I just didnt download it and everything is great. I wish it had 8 mic/DI inputs instead of 4 Mic/DI and 4 Line inputs, which I find have very low levels.