The weight will depend on wall thickness too.  In Australia, the 6 inch light poles have very thin walls and are quite light, possibly ok small boats.  For a given weight, the larger diameter section will be stronger than a smaller section with heavier walls.  Windage will increase but I doubt if that is a problem. In stronger winds, the sail is well reefed down and the upper spar has less weight and windage than a mast with stays.

Jonathan

That would seem a little on the heavy side for your boat. Other people have, however, used masts of those dimensions on a boat of about your size - see our mast database to see what other people have used.

Chris