I don't even consider IT an epic. Take out the easter egg, which isn't part of the song, and it's the same length as TCOT. And it feels very disjointed with that ambient section, and the breaks.
That's not a knock on the song though, as most of it is great, but its length is very artificial to me.
Octavarium is still easily the best of the ~20 minute epics imo (SDOIT is in a league of its own).