I'm miles from being a PT guru, but a late starter who got his Mix24 TDM system (2 cards plus 8-channel 882 io-box) for an amount to low to refuse, 200 bucks).
Thought: it's an Access Virus and can do some realtime fx, nothing to lose.
First impression: horrible visuals... but then it revealed more quickly then expected and it turned out rather usuable. Took about a month (maybe 2) and arrange and mix were quite convenient.
Most of that time trying out whatever plugins were available and settled with about a dozen 'essentials', trashing the rest.
I have 2 Windoze DAWs, one of them featuring a Creamware Scope System.
Native Intel VST never was my cup of tea, with very few exceptions, but I demoed a lot.
The interesting part: the Scope system has a different soundprint than PT TDM and Intel native is different from both. So this new color on the acoustic palette was most welcome.
(I'm not interested in competition, but in sound only - today one can find the proper tools in any environment)
PT HD (nor native) has been reported to be closer to Intel than to TDM's Motorola DSP sound.
TDM has low CPU demands (as most processing is done on the cards), I'm running it on a 2nd generation 450 Mhz G3 Blue-White from a 1GB Disk-on-Module that's plugged into the IDE connector. A copy of the DOM is on the shelf in case the active one stalls.
Project data is saved to a regular IDE drive atm.
Any G4 should be fine, but I'd pick a model with 4 PCI slots for extension cards sake.
According to my taste that 'TDM Sound' is a slight advantage as it got out of public focus over the years... disregarded for age and no updates, etc bla bla