Joe Bfstplk
Axe-Master
You are unlikely to see "Turbo only" features beyond having more room for stuff if you use the most demanding blocks. The number of Turbo owners are probably quite small compared to Axe-Fx 3 owners.
That extra HP is nice when you need it, tho....
Absolutely nothing is future proof in digital modelers. You will eventually see the Axe-Fx IV, then maybe an Axe-Fx IV Mk2...
"More future-resistant" is how I think of it. When you buy tech, you are buying a perishable product. Personally can't wait to see what an FM9 Mk2 or Mk2 Turbo will look like, with faster processors and the bigger scribble strip screens when it arrives, and the FX4 as well. Likely have a while to wait, but looking forward to them....