I was only in the Marine Corps for three years, but they were from the age of 17 to 20, and many of the things I was taught back then I still consider useful and important. Perhaps I’ve mentioned some place that my experience as a rifle instructor applies to photography. "Hold them and squeeze them" applies to snapping a shutter as well as pulling a trigger. Also, I am accumulating cameras and lenses in the same way I used to accumulate guns: A battery comprises a gun for every purpose one can reasonably imagine. I don’t accumulate guns any longer, but I am building something like a battery with cameras and lenses. Guns, will never wear out if they are properly cared for, but that isn’t necessarily true of DSLR cameras. They have only been around for a little more than a decade; so it is too soon to tell; so to be on the safe side, and if the price is right, it is prudent to back up the cameras one is especially fond of.
Also, I am constantly reminded that I never felt especially comfortable with a new handgun unless I had fired perhaps a thousand rounds through it, over a period of time, of course. I feel the same sort of thing in regard to cameras. I need to spend a lot of time with each camera before I feel adept with it. I was perhaps up around 10,000 shots each with the E-1 and E-520 before I decided the Olympus DSLR cameras were pretty good. And thanks to the influence of marketing, plenty of camera users were willing to unload their "obsolete" Olympus cameras with 100 to 500 shutter actuations in order to "upgrade". Why should I buy a new camera, whether an EM-1 or any other new camera when there is a thoroughly tried and proven camera available with just about everything the new camera has minus the bugs and in near new condition?
My “battery” rationale may be fairly weak. I do like to try new systems, but have no wish to try the latest and greatest according to marketeers and their reviews. I'm a hiker and when Olympus quit making DSLRs I found the Pentax K-20D, K-7 and K-5 to my liking.
As to the Micro 4/3, for the most part that is too new a system form me to switch to or try in any big way. I did however find an EPL3 on sale with the 14-42 kit lens for $199 and couldn't resist that. I've probably put about 500 shutter actuations on it and can think of niche situations where I'll be happy with this light-weight little thing. Choosing an EM-1 over a K-5 is another matter. I already have the K-5 and don't find the EM-1 at all tempting, even if the price were comparable to a K-5, which it isn't. I was acquiring only Olympus DSLRs, but when Olympus quit making them I began adding Pentax DSLRs, and the camera I'm most likely to buy next isn't the K-3 but the K-5ii or K-5iis.
I have added a third system when I acquired the EPL3. I like the idea of being able to look down into the articulated LCD screen in the manner of the old Kodak Duaflex camera. I don't have any "gritty streets" to walk in order to photograph "gritty street people," but I do find some interesting scenes when I'm not on a hike; so I fancy the EPL3 will come in handy. Maybe one day if the price drops low enough I'll acquire the EPL5. Will Olympus make an EPL7???