My mistake. Apparently, you can strum hopo's or overstrum and still get an FC. I think that an FC should be no overstrums or strumming hopo's. Is there a term for that? I've gotten 100% on a song and knowing that I overstrummed, I don't really consider that an FC.
Full Combo should mean Full Combo (i.e. hopo's and no overstrums) and not "hey, I hit all the notes and didn't lose my multiplier - yay!"