I can only reply with my experiences about the bass side of things. I have a miracle man, which has a LOT of bass, but is super tight, like the painkiller. The ability of your amp to handle the bass output might be what you're mistaking for muddiness from the pickup - in this case, boosting in front of the amp (thereby removing a little bass in the process, depending on your booster) will tighten the amp up a lot, still leaving you with bone-crushing bass!
Your statement that you've been avoiding high-bass pickups because they might be muddy implies that you want a tight pickup, then you go on to say you prefer a slightly looser pickup... which is it? :)
None of the BKP range will get flabby, so I wouldn't use the worry of that as a discriminatory tool in your pickup choice.
Hope this helps,
Roo
