I have two GH2's and a number of prime lenses for them. Panasonic 14mm, 20mm, and A Voigtlander 25mm. I also bought an adaptor for Nikon AI lenses and so use the 50mm 1.8 quite a bit. The last two lenses are manual focus, but focussing is very easy, especially at wide apertures if that is your thing. The only niggle is that it is very easy to accidentally push buttons with your thumb when you don't want to. But then that seems to apply to lots of small cameras. The GH3 looks as if it will be better in this respect. I think I would buy a GH2 over a G5 even if video was not as important to me - which it is. I agree that you will be much better spending your money on lenses than bodies. Spend the extra you would have spent on the GH3 on buying a GH2 (or G5) and a great lens or two. The images I get with the prime lenses are not so different from those out of my full frame Canon - and for much less weight. Lenses will last a very long time - bodies will come and go in the next few years.
Jim