The Manfrotto PHOTO RC2 plate doesn't block the door if you turn it in the right direction. However, I'm using it with an adapter to fit on the manfrotto video heads (503 type plates), so I have to orient it in the other direction, and have to loosen/turn it every time I have to change the battery. No big deal...takes a couple of extra seconds.
Yup, the Manfrotto 200PL-14 quick release plate doesn't block the battery lid if attached normally and they have a number of items using it. The most useful the 323 which I have a bunch of mounted on various other gear.
I use Manfrotto 577 adapters on my GH1s and they don't block the battery door. You cannot open the door completely but still open enough for the battery to pass through. On the photo the plate couldn't be put straight due to the knob of the Nikor/MFT lens adapter, it just gives you an idea of what it looks like. I find these adapters very suitable for the GH1 and they fit on the mid-range Manfrotto tripod video heads.