well, Gilbert does use very middy pickups
the most Gilbertish BKP i ever had was the neck cold sweat installed in the bridge, but that was in a maple neck Greco les paul
for an Rg I'd easily pick a black dog over a high output model
but answering your question, the miracle man is an amazing pickup and has a good history with rg550 model
comparing to dimarzio models, it should be closer to the stevie's special than to the evolution
bridge model has a really punchy low end with a nice treble spike wthout sounding harsh
it is extremely articulate on fast leads and sounds pretty focused and intense on slow leads
the neck model is darker voiced and has a fatter midrange, kinda more modern sounding