I upgraded from a M1 Max Mac Studio to an m4 max studio last fall, and the difference was noticeable. I run all the usual stuff - lrc, topaz, dxo, ps. As always, as I'm sure you know, RAM is probably the single best upgrade you can make, regardless of the machine. I have 128gb, and it screams on lrc, and moves on dxo. Besides RAM, I'd recommend getting at least 1TB internal, so you can put your catalog on the internal for better performance.
As for monitor, I went for the Studio Display b/c I wanted the better speakers and camera. But there are a host of 4k and 5k monitors that will work just as well, for less money.
Tough call trying to future proof, especially as high demand AI apps and app components proliferate.
Good luck!
Steve