And my dilemma is that I have both several FSU lenses and bodies for 39mm LTM, that obviously work well together, and an M2 plus a few M lenses.

I like the LTM lens better (just because), but I would like to move from the FSU to real Leica stuff. Obviously that's an expensive proposition. Especially when what I own now works fine. And I'm hardly making my living on photography. So it's a totally sunk hobby cost.

The camera body is a drop in the bucket.