Apparently, a new GH2 will be announced on september 21st and the GH1 is going down in price. The G series
isn't that much bigger than the GF.
I tried selling my Nikon gear for m4/3 last spring but nobody wanted it. I tried a GH1 in store and was impressed. I liked the viewfinder more than entry level DSLRs and it has more external controls too, and is still smaller. It's even smaller when you consider the lenses. The Panasonic are really "photographer's tools". The Sony seem to have better image quality but I do everything manually and the lack of controls would be a pain.
I'd say wait until you absolutely need a camera. Chances are there will be more of those "EVIL" system sooner or later. Samsung has a mirrorless system too.