I've had quite a lot of Leica gear over the years, a iiia, two iiifs, an M2, two M3s, two M4s and an M4-2, plus lots of lenses for them . Not a single piece--not a lens cap, even--did I ever buy new. For Leica film equipment I could never see a reason--it doesn't age poorly and seems to last forever, so I'd prefer to let the original purchaser take the depreciation hit. Once in a while I get the yen for a digital M, and if I do that, I'll probably buy a new one to maximize the time that it's relevant. And it does seem that recently digital changes are smaller and less fatal, so I might actually get a good decade or more out of a recent digital purchase.
But my M4s are now over 45 years old, and the IIIa is now about 80, but neither has obsolescence in sight, so digital doesn't look like a wise purchase, really.