I have switched to Pro Tools 8 a couple of months ago, after getting a Digi003. Although, I have barely used the extensive features that it offers.
At the moment I am on a PC (XP Pro, 4 GB, 2.4 Ghz), but the machine sometimes can’t handle low-latency recording with H/W buffer below 256 samples. Maybe I need an HD system. Also, sometimes I get sudden white noise bursts both in artists and my headphones – there can be a million different reasons for that though. Apart from that – I’m lovin’ it! That’s my experience so far 😉
But, from what I know, they still use PT 7.4 with MacOS Tiger at Pinewood – reliability is the key there.
P.S.
Even though it’s not relevant to the topic, I would not recomment switching to Snow Leopard to anyone – too much glitches and incompatibility issues. And that’s even after 10.6.2 update.