From a makers point of view, hat peg can be nice because the gears are relativley inexpensive and you can make the shaft with a personal touch. The pegbox does not need to be drilled or reamed to fit hatpegs, the shafts can be turned to fit the exsiting holes. As for the desireability of more or less wieght, do a search on Ao Bo matching on this site to learn about resonate frequency matching.