The point is, if what you like most about rosewood is the look, then you can either go strictly by look or find a denser, brighter sounding wood that looks like rosewood. You needn't necessarily sacrifice the brightness and density of ebony just because you think something else would look better. You should try to pick your guitar woods for their sound, not their look (unless the difference is marginal). To me, ebony always sounds better on a mahogany body than rosewood, and I would guess you wouldn't want to compound the lack of brightness you might expect from a mahogany 7 string body with a rosewood fretboard.
just my .02