Yeah, I like the generally classless nature of DD as well, I would just like it if there were more distinct advantages to developing the intelligence attribute, and additionally some way that greater intelligence would affect the warrior to a small degree and a mage to a greater degree. But maybe to do this and still have balance, you'd have to further nerf some of the Mage's non-magic abilities, and possibly even nerf some of the Warrior's non-fighting abilities.
Seems like Survivor is pretty much middle ground, except their damage per strength is just barely better than a Mage. I'm not seeing a distinct advantage to being a Survivor other than possibly that little boost to defense per agility.