Thanks for your insightful thoughts!
My philosophy on buying cameras so far was this: I don't care too much about the body, but the lenses. Well okay, I have a full frame cam and that was important to me for creative options and "clean" images as well as a big range of lenses to choose from. I like being creative and do different uproaches. Sometimes I go with an UWA sometimes with a macro only. I often need 1.4 at ISO 3200 when sitting with some friends at a restaurant in the evening or on a little party. Sometimes I use flash but I like the look of natural light there. FF is so flexible and good for what I shoot and like. (Not to speak of weddings, my porty flash or high res stuff)
But I think the OMD's have probably enough going for them to be a real consideration: Less weight, IBIS, creative options in live composite...and high ISO is getting better too.
An OMD is probably similar for landscape and walkaround - maybe even better because its much lighter. I just have to look for the pros and cons and if its worth it for me. Imagine I go on a photography holiday trip equipped only with an oly. Would I miss too much and what positive things do I get? The feel if a 1.4 lens on FF? High ISO good enough for me in the evening -> I think YES, because of IBIS and because 1.4 on FF can sometimes be a disadvantage in the evening.
I think weight is still one of the most important things for me, because 50% of what I shoot involves travelling. Otherwise I wouldn't think about another system, cause my 5D2 does an impressive job for nearly everything I love to shoot. And for weddings, some model shootings I will still keep them and for the 35 1.4 feel.
I will probably get one soon and try it for myself.
Thanks to everyone in this thread. 
I went from film of many years ago to a Nikon D60 DSLR which I enjoyed using. Then I got into the M43 systems with the EM-5, the EP-5, GX7 and now the EM-1. They are all great cameras and do a super job. However, they have definite limitations when compared to the big FF Canikon offerings or the FF mirrorless cameras available. I don't own and have not tried the big DSLRs with the fast zooms, but the people shooting with them can get much better results in some instances and I cannot equal them with the EM cameras with even the best native primes. For low light of action shooting (dark venues, auto racing, etc.) They can always capture images that I cannot with the M43 system.
For most other uses, the M43 system is very nice and will give excellent results. The cameras themselves are quite nice, easy to use, versatile and even weather sealed! The Olympus cameras have IBIS which is great and can accept many legacy lenses with the right adapter. I still have my M43 system, but I got infected with the Leica lust virus
and now I find myself shooting with the M240 a lot of the time...
