The M2 was made during an age when Leicas were hand-assembled, with all parts being hand-fitted. Its operation was very smooth when new. Thousands of film advances over the fifty years or so the M2 has been in use will have made it even smoother. It has framelines for 35, 50, and 90mm lenses.
The M4-P was made after Leitz switched over to a more cost-effective production method. They were made by CNC computer-controlled machining. There is really nothing wrong with that, they are just not made with "old-world craftsmanship" to the same extent as the M2. In exchange for that, you get a 28mm frameline in the finder. No need for an external finder for a 28mm lens. And you get the rapid-loading system that became standard on all subsequent Leicas. They are indeed nice cameras. If you go for an M4-P, you might prefer an early one, because the framelines will be a bit larger than the later production. That makes them better for framing at all but close distances.
About having the chrome stripped: I had an M4-P and I recall that where the (black) chrome was rubbed away, the underlying metal was silvery, not brass. So I think they have the zinc top plate. If you still want to have it stripped and repainted, the zinc is less good for that than the brass. That point would argue in favor of an M2.
