I have a 530 pro and have driven an SR4 and a 5.4, although have only been on a lake in the 4. The 530, compared to the 5.4 is more harsh a ride, no doubt about it, and it leans much less on the turns. On the other hand, the deck space is so much larger. The "flatter" handling is not a problem, just different and I've been out in the 530 in some very choppy conditions and it was good fun, and the boat coped admirably. I find the ride in the 530 to be much drier than in the SR's. I'd say try before you buy, but I guess I'm too late!
Hope this helps,