Me too... 5'7" with 30" inseam. I've ordered a 2013 F800GS with factory lowered suspension. From everything I've been able to determine, the seat height then would be the same as the new F700GS and based on that, it'll still be higher than I'd like but with care I think I'll be able to manage. I'll be on the balls of my feet on flat even ground.
Just about all of my use will be on roads, with occasional gravel or dirt trails thrown in. I just returned from a 10-day 5,000 km tour of New Brunswick, Nova Scotia (and of course the Cabot Trail) and the Gaspé region of Quebec. And there were many times I wished I'd have the new bike to better be able to tackle some of the roads I encountered. I did close to 10km on a very bad condition dirt and gravel road to get into the campground at Meat Cove NS and with my fully loaded K1300GT with road tires, it was challenging to say the least. And that's a bike I CAN flat-foot it on (thanks to the optional low seat).