Big chance. My flights IAD-PTY-LIM were showing 737-700 then 737-800 and on the way back it supposed to be 737-800 from LIM to PTY and 737-700 to IAD.
At IAD I boarded -800 and at PTY I boarded -700. On the way back I've got both flights on -800.
I am 6'4" and didn't feel cramped. Just don't drink Balboa beer. It was nasty