Ryan, I mounted my extension bed before I ever used the lathe. I figured that was as good of place to store it as any.
It's not too hard to move from one position to the other (especially if you've got someone to help). I've used in in both the upper and lower positions, although it generally stays in the lower position. I seldom have a need to turn anything as big as it can handle, but the lower position works as a handy spot to set the tailstock when I need to remove it from the upper bed.
I could see using the extra capacity for things like spinning wheels or tabletops. I've turned a couple of 22" to 24" bowls, and while the challenge is fun, there really isn't much market for bowls that size. They are hard to store, they're too large for most shelves, and they pretty much overtake any table they are put on.