Sperzels is what you want. I have them on one of my basses and they're very stable. Watch out for cutting strings too short - oh, and they strip the windings off of those coated DR strings. When I phoned DR to complain the support guy sighed and said "You've got Sperzels, right?" before I'd mentioned it and was offering to send me a new set of non-coated strings within seconds.
Turner Renaissance 5 string fretless
Bolin NS 5 (yes, I'm a piezo fetishist)