I can't speak for the rack, but I have a 002. Its sweet. Sounds great and runs great on my PC. I haven't tried it much with Mac other than to hook it up and see that it works.
I really like PT, but then I also use a TDM rig at work and like being able to take my home projects back and forth (and vice versa).
With the new ASIO drivers, you'll still be able to use it with SX. Had I to do it over again, and had the rack been availible at the time, I would have gotten the rack and a different control surface for just that flexibility.
Anyway- I've had 16 ins and outs going at once and it never hiccuped. I'm happy with it.
Take care,
Chris