Honestly. Mages do need some anti-aggro skill. In dungeons Mage becomes main target after using AoE, even Knight doesn't save me. I could just bring a Champ to AoE and have no problems staying alive.
I've played both Mage and Champ in dungeons, and so far Champ is much better for AoEing, it doesn't need recasting a silly skill "mana shield" to stay alive, no need to focus on buffs bar to see if Mana Shield is still active, Champ doesn't require so much effort as Mage, it's a lot easier class to play as you just need to spam skills and focus on HP.
But when it comes to 1v1 combat Mage beats champ. I've had tested my Mage and Champ on a Moldie King several times. My mage takes about 10~15 seconds to kill this boss where there Champ could take up to 1 minute. Mage has a very useful ASPD debuff skill "Permafrost Chill", where my spear Champ doesn't use any skills against boss and relies only on "Normal-Attack". In this case, Mage is much more useful at boss with it's debuff skills and high damage than a champ with a normal attack.
Now if we would compare a Champ and Mage endurance at boss, then a Champ would be a winner here. Sometimes I don't notice how my Mana Shield disappears, and if I don't recast it, boss like Ulverick can kill me in a single hit. There is no meaning for a Mage to look at HP bar anymore since it dies from a single hit. Champ can survive several attacks, it also depends on build.
In summary, Mage class has some nice tricks (debuffs and high dmg), but it's useless group member if it can't manage to survive. Champ doesn't have anything special, but it's pretty well balanced class.