Travel Photography - Roller Photo Bag on regional carrier

I'm travelling on a Colgan Q-400 and an Express Jet ERJ-145 later in the year.

Does anyone have any experience of taking a Think Tank Airport International onboard either of these regional aircraft, specifically with regards it fitting in the overhead or under the seat in front?

Honestly i'm not sure. It fits fine in the CRJ-900 and CRJ-700 overhead bins but without much room to spare. You have a decent chance but I'd definitely be prepared to remove the laptop compartment if you have a laptop in there.