Thanks for the info. Although I'm not really interested in the EM-1X, as an E-M5 user, I appreciate hearing your thoughts.
Two things:
-interesting about the optical performance comment on the 50/2. I got a mint copy a year ago, and find it underwhelming, mainly because of terrible CA - red fringing on high contrast edges, and noticeably lower contrast than my 12-40. I now wonder if mine has a problem. I did try it on the E-M1ii at release and found it focussed fairly well, but use MF on my E-M5s.
-I found it interesting that you compared the 12-100 with the 40-150/2.8, and not the 12-40. I guess that's because you shoot more telephoto than I do. For me, the 12-100 seems like a near perfect combo, giving me wide to reasonable tele. Whenever I mount my 40-150R, I soon find I am limited by one or more of: limited close focus distance, not wide enough, or not long enough... For me, I think a 12-100 for general purpose, and a 75-300 for tele (or 100-400) would be a good fit.
I do hope the E-M5iii is not far off.