One thing that's kept me from getting interested in online RPG games is that they seem from the outside to be nothing more than combat/mission games. This is fine for fantasy, but for a superhero game, I expect the hero's alter-ego to be part of the story as well. How many pages or even full issues of Superman have been dedicated to Clark Kent's life? A good portion, to be sure.
So my question, can anyone familiar with online superhero gaming tell me if you really get to play a character, rather than just a super-combatant?
On the surface, of the ones I have played in term MMORPGs - Champions-Online and DC Universe neither has gone that route. Certainly nothing official that you do as your alter-ego type.
I think that comes as part of super-hero RPG designers focus. They see the action as something that can have universal appeal and hits one of the main gist of the comic-book superhero. The element of hero background/personality tends to lean towards personal interpretation and for an RPG might be considered something that falls more into role-playing than online play. (Look at Clark Kent. Early in comics, he really was just a cover for Superman. The change was both to create new stories that appealed to their audiences as times changed, but also how the each writer wanted to handle the character changed.)
There's a little more of that kind of element in Champions, in that there are some social areas where one could RP some kind of background as your alter ego with other players. If I had to say there was a game that created more options for character stories and social role-play, it was probably City of Heroes in its day. There was always at least one server that was considered the "RP Server"(I believe it was Virtue) for that kind characters stories, and their extensive costume designer gave you plenty looks and options.
Anyhow - don't know if that fully answers your question.