I am relatively new at 5'ers but, so far, here is my experience...
-Heavier gauge strings have a more profound overtone "thump"...I use a 125 B with light gauge Elixer nanowebs
-I raised the action a bit...that seemed to help clarify the tone..kinda like a classical guitarist does
-Find the "sweet spot" on your bass. Mine is pretty even, but, still, it sounds great on all strings between the 5th and 12th fret.
-If you are playing with fingers on your right hand, try "floating" your thumb over the strings, muting when needed, instead of anchoring somewhere. I got this from a really great bassist I know, and it have really cleaned up my 5-string playing. Not so noticeable on a 4.
-Use a light touch on the B string.
Hope some of this helps. I have not played many other 5 string basses and am a bit spoiled with mine. I think the Ebony board helps as well.