Haven't used a BOB for touring, just panniers. My comparison is from my two methods of with-child-cycling.
I have a rack mounted seat for my 1 y.o. and a trailer as well. By far the rack-seat is faster...I mean, by far. The added rolling resistance plus the "drag" factor make the trailer immeasurably slower.
I've ridden pretty well loaded down bikes and haven't had a problem. Off road I would want a BOB, for sure, but on road the gyroscopic motion of the wheels keeps the bike upright pretty well.
I don't think I'd drag a BOB across country unless you paid me.