An interesting, but slightly ominous system.

I think that it will add a lot to soloing - e.g. players with a support type build can switch to Offense and hold their own - but in my heart of hearts I was hoping DCO and CO would be classless AND roleless.

Once an MMO has Tank & Healer roles available it is pretty much inevitable the devs will design foes which deal such damage that Tanks & Healers must be present to defeat them.
Then you can't go start missions/whatevers till you find a Tank & Healer...
To ensure there are lots of those players are expected to play up to max. level as joyless healbots and meat-shields...

"Healers are arrogant/extortionists/incompetent !" etc.
"Stop attacking Darkseid everyone or Ill lose aggro !" etc.
"Show build plz. Show build or I kick. Lmao you're not running ISPX240 on a E/T? Noob" etc.

Cannot we all just don our spangly spandex pants and ALL have good clean comic-book-violence-dealing fun ?