Interesting quiestion spaw. I think a lot of it depends on what style of banjo you want to play. As far as I understand it, the "Bluegrass banjo" was pretty much defined by Earl Scruggs using a Gibson Mastertone and the flat head tone ring itself is a pretty heavy item on its own.

People seem to want that particualr sound accoustically and for what ever reason, it seems that no other construction gives it. To the best of my knowledgs, the likes of the Stellings, Omes and Deerings favoured by the Bluegrass players are all based on the original Gibson design which also involves a pretty thick rim. These instruments are heavy without the resonator.

The Irish style tenor playing seems to me to be a lot more open with regards tone but certainly over here, the Gibson styles are popular and thinking of the links I gave you, Sully's top instruments are based on the Mastertone designs and the Clareen is based around the Gibson arch top tone ring.

In my case, I wanted a banjo with plenty of power. I used to do a lot of playing in noisy pubs and needed something that would cut through accoustically. Mine weighs a ton but it does that job perfectly.

Jon