I've ridden both, but most of my time has been on a 550 hull. The 550 hull feels much easier to throw around and I can get it to lay over in a turn better. The 650's seem to turn sorta flat to me. The 650 hull does handle a little better in chop, though because it weighs more.If 550's are modded correctly, they can be much faster than a 650. All my js hulls will smoke most 650's all day long and two of them will take a lightly modded rn sj. People have a lot of different riding styles and some people's styles fit the 650 better and some like the 550, so the best thing would be to get to try both. You can listen to everyones opinion, but at the end of the day, no one will know which one you like better than you.