I saw some Bungie guys talking up the fact that they didn't want characters to descend into the usual DPS, Tank, Healer type roles of other MMO's. I've started changing my config mid-strike for some instances (love the fact you can do this), and I'm wondering if this is more the way bungie want Destiny to evolve? Once you know you sub-trees and strengths, should be a lot easier to reconfig a team mid-way depending on the challenges ahead. Also means teams aren't restricted to always having a certain number of specific roles in them... be interesting to hear what you find works best for different types of encounter (with Titan's)