I've done 5 in a 10 frame box when I alternated foundationless with comb. They overdrew the comb right into the open space of the foundationless frames. What a mess, couldn't get any frames out without ripping the combs and honey spewing all over. :roll:
You will probably be OK if you use drawn comb, but it will make for more of a mess extracting as your cappings will have much more honey in them to drain. Personally I don't see the benefit even if the bees can store a little more honey in theory. Nine frames allows for thick enough comb for easy uncapping.