I don't have a B11, only the choil-less B10, so perhaps I should just shut up, but I will add my 2 cents anyway.
For me the B10 is just about the perfect large field knife - as much edge as you should ever need in a very light and compact package. I have no doubt that the B11 is a better chopper, but for me the primary use of a large field knife is not hard chopping, it is slashing / light chopping and batonning. A folding saw of some variety is a much more efficient way of getting through a large piece of wood across the grain. So as a real-world user in the boonies, I would go for the B10 (+ saw + small blade).
Having said that, big choppers are fun to play with. I'm not looking to buy a B11, as I doubt it would provide that much more than the B10, but if Busse came out with a B12-14, I would be all over it.