Interesting offerings! If I still used an APS-C dSLR, I'd be quite interested in the 10-18 IS. For the EOS M, I'd prefer the EF-M 11-22 IS (ordered from overseas) over the 10-18 with the adapter. The EF-M 11-22 looks to be optically better (based on MTF charts), has a metal mount, etc.

The MTF curves of the 16-35/4 IS are impressive for a UWA zoom, particularly compared to the 16-35/2.8 II (even af f/8). Looking over my library, less than 15% of my 16-35/2.8 shots are wider than f/4, and many of those are of static subjects where 3-4 stops of IS would be of more benefit than the extra stop of light. I suspect the 16-35/4 IS would be a viable replacement for the 16-35/2.8 II, for me (although given that I have the 24-70 II and TS-E 24, the 82mm filter diameter of the f/2.8 lens is more convenient).