i have both
I'm about 6'1" with shoes on and about 33-34 inch inseam. My large KM was set up single speed and I was totally digging it except I started wishing it had a little more clearance over the top tube. So I asked the same question you're asking over in the 29er forum and got a lot of different opinions. It appears that there are quite a few people about 6 ft tall that love the fit of the medium. So I ended up buying a medium to try. I've only ridden it 5 times since I put it together, but so far it feels much better than the large. Weight distribution definitely changed, but for the better as far as I can tell. It feels like the weight is more evenly distributed over the front and rear wheel. I have a jones-hbar with a 130mm stem and my seat is way back on the rails, so I've pretty much maxed out the cockpit length, but it feels good for me. Of course, if you have a much longer reach than me, you might feel cramped. If you don't want to go custom or with another manufacturer at this time, there's not much risk money-wise in trying a medium KM, swapping your parts, and then selling whichever frame you don't want. Or keeping them both, like i did : )