For a forum that's nominally just about a retro camera, this thread is very interesting.
First, the MP - I want one. I had a previous M3 "Frankenstein" that had been modified while I owned it beyond recognition - M4-P viewfinder (I used the 35mm lens rather than the 50mm as my primary lens at the time), beat up old brass top plate painted roughly in black, Tom's Rapidwinder in black, M6 claw loading system, M4 advance lever & one of those aluminum rewind attachments on the rewind knob. I loved that camera.
To me, the MP has all the features that I had put into my old Frankenstein M (except the M4 type advance lever) plus internal metering. This is the camera that I've been waiting for.
To questions about the old style advance & rewind controls - I'm currently using an unmodified M3 (well, it's actually an old double stroke that was converted to a single, but that was done before I bought it). If you're using an M4 or newer Leica M, it's pretty easy to adapt to the old style controls. Altho' I do prefer the M4 advance lever, the M3/2 lever is still shaped very nicely. Adding the rewind accessory (as on my old M3) helped a lot on rewinding, but even on my plain, unmodified M3, it's really not that slow. Also, supposedly the MP's rewind's knob has built-in friction, so if you let go of it accidentally, the film inside won't unwind. That is an annoying trait with the M3/2, so let's hope they've fixed that on the new MP.
I'm looking forward to getting both the Leicavit M & rewind attachment, in addition to a black MP. I think Tom's Rapidwinder is great (& he's a nice guy on top of everything else) & is an extremely well-made, reliable product. If I had to nitpick, the only minor disadvantage on using the Rapidwinder is it would make the regular advance lever (if you switch back to it on ocassion) heavy to pull. I'm wondering if the Leicavit M will do the same thing.
As some of you mentioned, it would've been nice for Leica Camera to have offered an MP 0.58x in black. But since I don't use the 35mm focal length anymore, the 0.72x probably makes more sense for me. The 0.90x M3 is a great finder for the 50mm, but sometimes with glasses it makes it difficult to see the framelines.