Here's a photo of the Super Ego under the seat in first class of an AA MD-80:

It appears to be sticking out quite a bit, but it is actually completely under the seat (you can see the seat strut peeking out next to the left corner of the bag). I got upgraded to first class on the American Airlines domestic flight, but I was in the back of the bus on British Airways and the Super Ego fit perfectly under the Economy class seat as well.
Thanks again to everyone for their insight.
Leave a comment: