I have, and use, 135 mm lenses on Leica Ms, both film and digital. My favorite is the oft-maligned 135 2.8 Tele-Elmarit. It's part of my daily kit and very handy when I don't want to mount a Visoflex and the 200, another wonderful combination. If you want to use just one rangefinder body, the 135 is about as long as you can go without adding kit. I use mine for scenery, sports, animals, and at fires. On a keeper level, it produces as many good shots as a 50 Summicron or a 35. But that's just me, for others, it may not be a handy lens.