I seem to remember a recent thread here discussing this issue - do a search, there were some good opinions expressed. And here's mine, for free!
I think the decision between the two boils down to what you are going to use it for. Basically, if you are tracking live bands, or any situation where you need multiple inputs and outputs, latency-free monitoring (for headphone feeds), big track counts (32+) and in especially if you are charging people on the clock and need to deliver without a lot of hassle, a TDM system is for you.
On the other hand, if you are primarily a "bedroom" studio, solo artist working mainly by overdubbing, or only interested in mixing/editing/post-production/etc., an 002 and a high-powered computer will probably serve you very well.
As far as stability goes (AlexLakis) a properly installed Mix system will be extremely stable. If it's not, it is not ProTools that is the culprit - more likely the problem is caused by version mismatches, cracked plug-ins, or some third-party software on the system.
And yes, Mix systems are version-limited - you can run up to ProTools 6.4.1. You are also limited as far as Mac OS - officially 3.5 (I think) although I am currently running 3.9 with no trouble.
And there, for free (which is about what it's worth) is my very own opinion.
best of luck,