Our Britax Boulevard with the GoGo wheelie attachment has fit in every seat--Boeing, Airbus, CRJ and EMBs. The only issue we've ever had was when the arm rests on a RJ didn't go up and so made for a tight fit.

We have also had the issue about the pax in the row ahead not being able to recline the seat. When he is forward facing the seat ahead can recline but that puts the seat pretty much in his lap! So, if the pax is okay with the free back massage then they can have their recline. If the seat is mounted rear facing, the seat ahead absolutely cannot recline.