Gladiator skills are very feeble at the low levels. I think unless the DPS are only hitting a single target then it's hard to hold everything, and even then your skills designed to raise enmity only barely keep you ahead of enmity drawn by others in the group. In my experience, a lv50 paladin playing endgame encounters is much easier to hold enmity, so in regards to that aspect the game gets easier as you progress to more difficult content which is odd. Low lv dungeons are harder to manage enmity but I wouldn't worry about it.