I agree most people would be overweighted, but that does not prevent you from making a controlled descent. I am naturally negative in an al backplate with an al tank and a 3 mil wet suit. I can still make a foot per minute descent with no exposure protection in a set of steel doubles with a steel backplate. I can still hover at any depth.
If your wing is not big enough to support your rig, that is the problem. But any competent diver should be able to make a controlled descent with an Al80 on a steel backplate with no exposure protection and a 17lb wing. I would wear and recommend aluminum, but there is no reason for anyone to sink like a rock.
