From Dark and Darker Wiki
< Gear score = better loot drops?
No, the loot tables are the same for all three brackets in normal lobbies. >25 you will obviously face players who are stronger than <25. The only benefit is that you'll have an easier time with PvE. Personally I don't bother going into 25-125 lobbies. Starting in a lobby <25 you can easily find decent common gear to raise your gear score before going into the lower levels. Ice cavern might be the one map I might consider going in >25 because it only has 2 levels vs 3 in the ruins. Plus, it makes it easier to fight the wyvern if you have better gear.