First, I have a smallish camera bag, the Domke F-5XB. It has enough room to pack both cameras, but leaves no room for additional lenses. I find it extremely bothersome because I don't want to carry a bigger bag, and I don't want to feel like I'm sacrificing something by not having the right lens with me. Since the OMD with PL25+hood actually take up more room than the M9 with 50'Lux, I feel like I'm not feeling the "compactness" I'm suppose to get from the m4/3 system.
Lastly, and most importantly, M9 files are just unbeatable. Many nights, I would import the raw files from the OMD after I've processed the M9 files from the same event, and I would notice a big gap in the image quality. I've spent too much time tweaking the OMD files to try to match the colors I would get from the M9, when I barely need to do any adjustment to the M9 files. After a while, I just rather leave the OMD at home, or only take it if my wife would use it.
While the OMD does seem like a good compliment to the M9, I still shoot normal stills and portraits most of the time. Maybe if the OMD was my only camera, I would be happy with it. Ignorance is bliss. But I've been spoiled by the amazing images I get from my M9 that when I use the OMD, I feel like I'm compromising on quality. So for now, I think I'll let go of the OMD and give the Sony RX100 a try. The Sony RX100 is small and pocketable, does 1080p videos nicely, is very wife-friendly, and I would never have to debate which camera to use.
How about some images to illustrate my point? Here are some recent M9 shots with minimal processing: