I went from having a E-P1 with 14-42 and 20mm lens to a 50D with a sigma 10-20, sigma 30 1.4 and about to get a canon 70-200L F4 IS.
Long and short is, as wonderful as the camera and lens were, the stuff I really wanted - fast portrait lens, UWA was either too expensive or didn't exist. I also wanted shallower dof. My E-p1 didn't fit in my pocket and neither does my 50D either.
To my knowledge the lens are still expensive and there's no magical 40-50mm sub f2 portrait lens.
I enjoyed taking photos of jets at RIAT and Farnborough airshows this year, I think it would have been next to impossible with MFT gear to do the same for the fighters etc.
If I had the chance I'd like to pickup a small MFT body just for the 20mm 1.7. That lens is absolutely superb, and coupled with the 4 stops of IBIS, untouchable as a lowlight machine.
I'm also a bit wary of m43 going the way of 43.