Lets sum up - you can roll any aircraft if you have enough energy to play with - if you do a proper barrel roll by the book you will get an acceleration somewhere between 1 and 2 g if you dont overdo it - 720 has been rolled (for nothing more than spits and giggles to my knowledge)... Concorde has been rolled multiple times as far as I know, don't see why you couldnt do it on say a 737-700 today.