Upload & Sell: On
The SMCP-M 20/4 is very nice. It's sharper in Zones A and B than my (best-of-three) Oly 21/3.5, while it lags behind the Oly at the edges and corners. It's actually slightly smaller and lighter than the Oly.
Just before going on a trip two weeks ago, I shot a head-to-head comparison of the SMCP-M 20/4, Oly 21/3.5, Canon 16-35/L II, and Fuji XR 14/2.8 (first three on 6D, last on X-E2), which I will post here in a few days. Basically, the SMCP-M and Oly are both spanked by the newer lenses.