I've only just moved up to 50NL and have had some success at 6max and made a tiny loss at full ring, but here are my thoughts.
50NL doesn't really possess a more difficult challenge than 25NL. There are still plenty of fish out there that will call preflop AI when you have a monster with KQs etc and camping still pays off. The only difference I've noticed is that people respect re-raises a bit more (not that much more though) and play is generally a tiny bit tighter.

There do seem to be more people that know what they are doing, and I have been owned a few times with some good play, but in general if you look for a table with a lot of preflop raises and a lot of showdowns, a tight-agressive approach should pay off (or at least it has for me). Hitting two-pair/set or better and pushing when you feel ahead seem to be the way to go here...