I installed the Dexter EZ Flex and it didn't help with the Chucking. The advantage is that you have heavier shackles, wet lube bolts and it helps the suspension of the trailer by providing extra cushion.
To answer an earlier post, the chucking isn't necessarily caused by the pin not seating tight in the hitch. When I had the Reese slider I had a lot of back and forth movement. I have a Curt non-slider hitch now, which is very tight around the pin. I towed two different fifth wheels with it. The first one didn't have any chucking. The second one, much heavier, does chuck when towing.
2007 Cardinal 30WBLE