@saadnation: I just tried it and got as far as level 51, which is around about when those dreamrunner (sp?) dual-wielding dudes appear.
If there are 2 of them I will use my devil trigger. With one, the easiest thing to do is run away from them until they teleport then dodge; you can normally always get a few hits off after he comes back in. My biggest problem are the catlike enemies. They continue to rock my shit at around level 83 or 84ish.
Also, the biggest pro tip I can give is managing the enemies you see on screen. If an enemy is off screen they will not attack you.