I have first gen S5 seats. Yes they are expensive. However after using them for a whole season I can tell you that they are a game changer, Properly set-up and adjusted I NO LONGER have to stand up or lean to drive the boat, even in 3 meter seas. Not sure if I would still be guiding without them or, suffer bigger back problems than I have already...
A few of the guys have the Smooth Moves and seem to be happy with them but, seem to be quite bouncy.
One other note: My 1st gen seats are welded stainless tubing with Bentley River Runner seats mounted on the base. Way more cushioning than the newer stock units. The newer bases are cast aluminum. Some sqwaking about lose fasteners on those as well.