11-7 is rare, but not unheard of. Proponents of the 11-7 allocation argue that it gives top-liners a little extra ice time and make the defence more resilient to injuries in-game.
Having said that, I do not think it is the best use of the Sabres' players. Because I expect the allocation to be 12-8-3, I think they are almost forced to do 11-7 in game.