As it is pretty easy to do it I would do without any hesitation. Even if you are not confident to do it you can send lens to Leitax guy and he will do it (50 Euro) + parts. Personally I think that Leica you have is great Macro APO lens and very sharp. I like Leica colors and micro contrast. I was stupid when I sold my Leica lens kit (all 3cam - 28, 50 and 80mm) but I converted them already for Nikon and buyer insisted on them, together with other manual Nikon Ais lenses...
I have Tamron 90mm (52BB) and it is excellent lens but I do not think that can get to Leica level in terms of micro contrast.
Just a hint try Mamiya 645 lenses and tell me what do you think about it (colors, contrast, etc.). You might get surprised. Personally I love the color rendering of those lenses.
---------- Post added 07-30-15 at 11:58 PM ----------
Originally posted by Canuck_west Sell the Leica, buy the Pentax 100 macro, use the extra money for a good bottle of scotch. 😀
I will give him that right away for that lens...