a furniture question.

I've been thinking for a while about buying a proper bed frame, with a headboard and footboard even!, instead of the mattress-store frame that's been under my bed for lo these many years. The mattress-store frame is your basic five-leg frame - one at each corner and one bang in the middle, which I quite like, because it stops the bed having quite as much of a big divot in the center. Especially as I have it up on lifts, which makes it about a foot off the floor instead of just seven inches, and allows me to fit banker's boxes under there (as well as some other storage, but the banker's-box-clearance is the main issue).

Most of the beds I've been looking at brag about how their frames have six legs, which appear to be one on each corner and one in the middle of either long side. That seems to be to be asking for trouble if I put it up on lifts - but on the other hand, they talk about having nine and a half inches of clearance under the bed rails, and if there's no support in the geographical center of the thing maybe it's designed solidly enough that it won't sag even if the feet are propped up? Or, alternatively, if there are nine and a half inches of clearance, it wouldn't need six inches of boost to get a banker's box under it, would it.

Thoughts?