This is what i have noticed in plvling in the same spot for over 1 month. All drops seem to be random be it +1, uni, elite, ect, mets, db.
The only thing i have noticed is if i get a high lvl of met drops, the other drops are low, ie little if any +1, uni, elite ect, same with them all if met drops and item drops are low i tend to get db drops, yes i have had multiple dbs drops in the same area on the same night. if +1 are dropping low drops of dbs , +1 ect.
Other than that its all pretty random, ive tried with multiple classes, no real sign of class specific drops, i have heard a rumor that db buyers get their email addy flagged and get better drops after buying dbs. It is possible to set drops for specific types of ppl ie in tc only low lvls get skill book and weapon drops from pheasants.
also i personally find that rare drops, +1 rings, +1 ears ect are mostly dropped in the second maps, new map in pc, 2nd map in dc ect.
dont know if it helps but its what ive noticed