I had this 21 Elmarit ASPH for a few years and quite liked it. It worked well and straight-forward with the M8 with no corner or side tint corrections needed, with effectively a 28mm field of view. On the full-frame digital cameras it called for some correcting with CornerFix. I eventually replaced it with the f/3.4 SEM mostly for that reason.
Here's one shot with the M (typ240), and you can see that the Elmarit ASPH cleans up nicely with CornerFix... It won't need that post-production work when shot on film, should be excellent, Tom!