Bottom Line: Do you use them or not. If you do use them, and plan on using them in the future, then don't sell. However if you don't use them, have other M cameras and lenses that you use, then sell them. I had a number of M camera bodies and many lenses. I re-evaluated what I really used in the last few years, and decided what I wanted to keep. then I sold the rest. I have No regrets. I kept my mint M4-P, 35 Summicron version 4, 50 Summilux, and 90 Elmarit-M. This is the combo that I travel with and enjoy using the most. Can't justify the price of an M9 so film it will be for me. I also use my Mamiya and 3 lenses when I do Landscapes and need/want a larger negative.
Regards,
akitadog