Roger Hicks
Veteran
So, why buy a M2 or M3 instead of a cheaper rangefinder then if it doesn't matter? The body completely matters unless you are immune to ergonomics and design.
Exactly my feeling. And I find the MP to be a detectably nicer than anything between the M2 and the MP, as well as being a lot newer. Not a vast difference, but detectable: certainly not hype. Whether the improvement is worth the money is of course a personal decision.
As for lenses, even I can't tell, a lot of the time, whether I used a Leica, Zeiss or Voigtländer lenss. Except quite rarely, and then in most cases only at full aperture, the differences in shooting actual pictures aren't all that great. Not as great, certainly, as the difference between a good picture and a bad one.
So I'd go for the body first, and change lenses as and when (?if) you feel the need. No, it's not 'the lens that makes the picture': it's the photographer. And the photographer will most likely make better pictures with the camera he/she likes, regardless of what the test charts (or the internerds) say about the lenses' technical performance.
Cheers,
R.