I use my TT-33 as well as Cz-52 as a primary sidearm when I concel carry. Both are excellent firearms. There is little question the 7.62x25 is a very accurate and powerful cartrige. Not sure I'd care to have a TT-33 in 9mm for this though. You would lose a lot of velocity and I'm not sure the gun was really made or designed right for it. I've fired the M213 and it was not aweful but my 1945 TT-33 is a hell of a lot more accurate (when I do my part) and it feels better IMO. It really does feel like the gun balances differently.
A big drawback of the TT-33 design is it does not have a safety and the half arsed addition added to them pretty much sucks.