Seat for Jungle Wheels

Does anybody use the seat attachment for the Jungle Wheels? What did this accessory cost you? Any input will be greatly appreciated. I recently purchased a set of Jungle Wheels and my knees are already sore from being used as "shock absorbers".

 

I was going to ask the same question and found this thread in the search. Unfortunately no one replied. I thought I'd bring it up again and see if anyone is currently using the seat attachment. I'm thinking about getting one this season.

 

I recently purchased a set of Jungle Wheels and my knees are already sore from being used as "shock absorbers".

What do you think your back and kidneys are going to be saying when you put the seat on there and sit and bounce, bounce and bounce all day??? I thought about something like this a long time ago, but decided not to do it for the reasons stated.

 

Premo, I could be wrong but I think the seat post sorta flexes. At least it looks like it would.
It's not a straight pole post, but rather looks like a flat bar that's kinda bent near the middle allowing it to flex.

This is strictly based on the photo I've seen of it.

No one has one?