I have paddled many used boats in the past 3 years - can't make a decision with all the available boats - so been playing the field.

I have been pretty critical in the past on JK quality, reliability and durability.

SuperFun (I think a 2006)
Superstar (very early introduction)
SuperHero (the initial very un-fun, very poor floating boat)
Rocker (initial one, jammed myself into it)

All of these were 2007 MY and prior, and all shared the same attributes
1)Very heavy wear at the bow and stern on the underside of the hull, where the rocker transitioned to the underside of the hull. Do not know if there was a stress concentration from the seat structure, but the plastic was very thin and very flexible.
2)Also a weird spot behind the cockpit that was very flexible.
3)The usual warpage as well in most of the usual areas.
4) poor fit and finish, and not very good ergonomics for the "large but not huge/obese" crowd

I do like the low mass of the boats, and was pretty happy in the superfun (even more looking back at it)

I was looking forward to evaluating the MRocker as a replacement creeker, but after the undercooking poor press, I was not willing to waste time and or money, mind made up on Jefe Grande 
(I am heading south to eval a "new" Superhero though - looks pretty nice)

I have flotilla of boats in the old garage, and few have shared this issue/location. I have an older Riot Prankster and a Z, each with hundreds days of underskilled abuse, without the plastic quality or fit n finish issues that I have seen with these early JK boats.

so, good designs, poor engineering and manufacturing


my opinions

gregW