I have used both the 35 and 50 Summicrons in the past but I don't have them anymore. I replaced the 35 "red dot" with a "blue dot" Zeiss Biogon. Pretty incredible lens. Almost too good if that is possible. The 50 was replaced with a Hexanon, then that was replaced with a converted 50mm Pentax-M f/1.4 lens which is just fantastic, although it focuses the wrong way. I have some Contax Sonnars that fit with an adapter which also focus the wrong way. I am pretty happy with the 35mm Biogon and the 50mm Pentax and use those two lenses most of the time on a Hexar RF and a M3.

As far as losing money on a Leica lens, I don't think that is possible. They have been increasing in price the last few years and I doubt that trend will diminish. Most lenses are two to three times the price they were just a few years ago. Camera bodies have remained about the same though.