I made that move. I've been using m43 for about 2-3 years and I bought a NEX-C3 and am selling off most of my m43 gear. I sold my GH2 and 14-45 and 45-200 zooms. I am going to keep 1 or 2 bodies (a Panasonic GX1 and either an E-P1 or a GF2) and 3 primes (Panasonic 14/2.5, Panasonic/Leica 25/1.4 and an Olympus 45/1.8) I came to the NEX because I really love using manual focus lenses. The ease of adapting lenses is what brought me to m43 from my DSLRs. As a platform for using legacy glass I think the NEX is unequaled. The IQ will knock your socks off, the color is quite good (although can be over saturated much like the fabled "Olympus color" and overall the NEX is a real pleasure to shoot with. I don't particularly like the UI...but I have never liked Sony's UIs. That said, I have my NEX-C3 setup the way I like it and armed with my Konica 24/2.8 or Olympus Pen-F 38/1.8 it is a real pleasure to use. It has become my first choice when I want to make images. I am keeping the m43 setup because frankly NEX doesn't have a great selection if native lenses. The good ones are REALLY pricey like the Zeiss 24/1.4 and too few. If I was to pick up a native lens for the NEX it would probably be the Sigma 30/1.8 but for now I have chosen to make my NEX single purpose...a digital platform for my legacy lenses. My m43 is for when I want to use AF or generally move quickly and bit a bit more spontaneous. Right now they seem to co-exist comfortably. S0 while I did consider selling ALL my m43 gear until NEX has a more mature set of native glass I'll stay where I am.
Future gear shifts? The C3 really is giving me what I need and I am not finding that I need or want and EVF. I even sold my GH2 on the m43 side so no EVF there either. If NEX ended up with lenses that can hold their own with lenses like O12/2 P14/1.5, P20/1.7, PL25/1.4 or Olympus 45/1.8 (optically and affordability). I would consider jumping entirely to NEX and at that point I would probably look to whatever was the current version of the NEX7 for the additional controls.