I only have one m4/3, and that is the Lumix G1 which I bought when I it first came out. I am currently in between Leica M body (waiting for M) so I use the G1 with my Leica lenses. I tell you, I really like the G1 image quality. I'm sure the EM-5 is even better. At less than $20 for the adapter, what I paid for mine, it is easy decision. I also find that focusing is quite easy with focus peaking on the G1. Not sure if Oly has that. In fact, on my G1, I do not have a single m4/3 lens. I sold the kit zoom a long time ago. I bought a Pana 25mm Summilux and was not too impress so I sold that too. I used my 35 and 50 lux on the G1 all the time. I also have very good result using my 85mm Sonnar ZM on the G1.