Wfevans4, carelesslove, here !
You posed a good question ! I own and regularly shoot both a 4" M629-1 and a M629-2 Mountain Revolver.
In every way, the regular, old M629-1 is noticeably heavier - and even in 4", it seems comparatively muzzle heavy.
I shoot these revolvers at 3 distinct velocity levels: 800 fps (to mimic .44 Special), 1000 fps, (for higher, but sub-sonic performance), and near full-house level (cast lead & jacketed).
At ~800 fps, both revolvers are pussycats, with no appreciable difference. At 1000 fps, the difference is relatively minor and certainly not objectionable. It is very much like shooting a 4" N Frame .357.
At full-house levels, the nod must certainly go to the heavier revolver - and - to me, recoil & blast, is objectionable in both.
So, if you reload, and 1000 fps is adequate, the Mountain Gun / Revolver selection would be an excellent choice to shoot & carry.
If you are relegated to factory (max) loadings - go with the heavier revolver, knowing that you might never "get used" to the recoil & blast.
I hope this helps.
Tom "carelesslove" Love