I replaced my 35mm with the M645 and love it. I normally carry the 80mm(2.8), 55mm, and 35mm. I find that I use the 35 more than the 55. I have the 150 and carry it when I think I may need the longer lens. One thing I like about the M645 is the easy MLU switch. And there are lots of accessories available at KEH and on eBay.