I usually use a hardwood bridge.  But sometimes a threaded rod with nuts on each end.  Sometimes that   is sitting on top of a thin piece of hardwood.

I was looking at two of my diddley bows last night.  One sounds real good, the other like crap.  The only major difference was that the good one had a wood bridge and the bad one had the threaded rod atop a piece of hardwood.  I quickly made a walnut bridge and replaced the threaded rod.  Voila.  Sounds real good and louder too.  You  just never know.  I have found on some builds that the threaded rod sounds better.

I use the CB Gitty Zerbrawood bridges a lot and like them.  I also Make some of my own out of Walnut.  They also work good.

My bridges are almost always floating.

My conclusion is that if you don't like the sound of your instrument, try changing the bridge material.  Sometimes it is an easy fix.

Don't get stuck using one method unless it always works out well..