It is really a marginal difference, if any. Masts have always varied in weight by several pounds depending on the extrusion. I have owned 5 different 16s in my history and was racing heavily during the transition. I do not recall a big difference in stepping weight or sailing characteristics. I don't recall weighing one though or comparing that carefully.

Take away that big head casting, allow for the tappered thickness in glass as it goes up the tip and I would bet that inertia is very similar. In racing the boat there really is little difference and certainly higher winds have shown to favor the slightly different bend at the top.