I'm one of those using culls in my micro tanks (think 1g down to 1cup) and-- despite putting them in conditions that I wasn't sure they'd even survive in-- I'm now finding myself having to cull again: I've got berried females in two of my smaller vases and with so little volume I can't afford to add to the load.
While I understand the fascination with brightly colored shrimp, culls are sadly underestimated. For most of my tanks, amanos and ghosts can get too big and too obnoxious, and high grade dwarfs would *detract* from the natural layout. Tiny dwarf culls--brown or greenish, lightly spotted, transparent or nearly so---are perfect. I can have a whole swarm of 'em tucked unobtrusively away in the underbrush picking away at algae and debris, merrily doing their jobs and providing the occasional live treat for my larger fish. It's fun seeing what variants are thrown as well--pretty amazing what can happen when you just let 'em go wild.