This is a debate that I have where the true answer may differ from person to person.
Let's see what do you guys think about the following statements. I split it into two sentences so it's easier to read:
-"If you have any number of E-TTL capable flashes (say two 580EX II) set and triggered in E-TTL (by say the on-board 7D wireless trigger) to take a picture of a subject, it's no doubt a E-TTL exposure at the end."
-"When you add any number and any form of user-controlled manual flash (for example, a 580EX II in manual mode or a studio flash), the final exposure is no longer considered E-TTL even though E-TTL can co-exist with the manually-controlled flash(es) in the final exposure regardless whether it's a supplement."
I'm going to ask that question for now just so everyone is on the same page. Let me know if you don't understand any of it.