Steve - I've tried the Emerson bridge on my SS10 frailing banjo. It does seem to increase the volumne and perhaps the high end. Changing the "no-knot" tail piece to a more solid tail piece may also have helped achieve this, however.

The Emerson is very thin and the feet (three) are very small, almost pointed. You can really notice their imprint from the underside of the head.

A friend of mine has put one of the submerged wood bridges on his Stelling. He says it makes it sound slightly better, not a big change, but an improvement in tone. I heared him play this past weekend and wasn't aware of much difference from the front. But his Stelling always sounds good.