Any given stake to the next stake up will not be as different as it seems. Try hard to think in terms of blinds instead of $ amounts and try to forget that it's not your usual limit.

That said, the main difference in stakes is the ratio of decent players to fish. You'll find more decent players and fewer fish at each stake. That's why 4bb/100 hands is kind of low at 2nl and pretty standard at 400nl.