Trying pickups and pre's is an expensive hobby, particularly if the only reason you are going through hoops is down to loud drummers and guitarists who cant play quiet.
Jazz and folk upright players generally don’t have feedback problems, it's mainly the poor sods who are trying to compete with band members who don’t appreciate what an upright bass should sound like and really only want to hear an electric.
I've had a guitarist band leader insist on upright bass and after a request that maybe we turn down bit i get "sorry mate i dont do quiet" brought my Fender to the next gig and that's the last one i did.
The louder you go with upright the more it has to sound like an electric, i think that's what the pickups that are less prone to feedback do, my Schatten RB1 is great but it's very middy and electric sounding, no one notices or cares at high sound levels tho, the main object is that it doesn't feedback.