OK, so I'm gonna give you my opinion. Disclaimer: don't think I question your decisions or want to tell you what you should do.
From my point of view you need an updated system, fast CPU, stability and compatibility with your workflow.
I've never liked PT, had it on my engineer's studio (on a hackintosh btw
). Maybe I'm too young and inexperienced to like it, as I haven't even seen an analog mixing console in my life, let alone use it... BUT, if were going to use PT, I'd use PT Native, with the most awesome interface I could afford.
So, you need those two TDM only plugins, fair enough then, but here's what, in my opinion, you could consider:
gabriel g said:
"buy new mac pro: 2700€
buy protools 9 native 500€
buy any top class interface that runs firewire and has total delay compensation or no latency at all.
for example Metric Halos 2882 : 1600€
Hook up your converters via adat."
around 5000€
My question is: Are those 2 TDM plugins worth the additional 5K€ considering an outdated system, that's gonna drive you financially crazy?
I think you are amazingly talented, and you could even sound almost as awesome as you do using Reaper's stock plugins.
Anyways, I have a friend that not long ago was trying to sell his HD3 system (Spain), so if you want I can make a call and ask him about it.
Best wishes and good luck whatever you end up with!