It depends on how many skills are available and if there are stats that increase damage/support output types of skills. For example, if someone were to play as a warlock and there was a DPS tree and a Healing tree, having separate classes wouldn't matter unless there are "stats" that help increase your magic DPS vs. your healing abilities. So going a priest class would give you the added points for healing etc and going a battle mage route would increase your DPS abilities. I like that, but (and I keep bringing up Borderlands 2 jeez) I really like how Borderlands 2 managed different "classes". You had an item which dictated which "secondary" perks you would get (instead of stats because there are no 'stats' in BL). So if you went down a support tree and had a "Nurse" class mod, you would get faster health regen because of the class mod. So the "change" to this secondary class wasn't permanent like it is in a lot of MMOs -- you could just swap out your item. Though one thing I do miss from MMOs that had secondary classes is gorgeous specialized armor sets for secondary classes!~