The air seat
I have a nimbus gell, and a kh air seat, and have used them both on my 36.
Stock, the air seat is kinda lame. It gets misshapen easily, and if you run it soft, the ass bones tend to push the tube up into the frontal sack space. Not comfortable. If you run it hard, it’s not really more comfortable then the nimbus IMHO.
The fix is fast and cheap. Find a piece of closed cell foam. The cover is held on with a draw string closure, and can be removed or replaced in seconds. Position the inner tube centrally, and duct tape it in place. Then duct tape your foam over it.
This simple mod allows me to run the seat at about 5 psi. The foam keeps the air tube from popping up in front. The low pressure gives excellent comfort, and a bit of suspension. Best 36 seat I have tried so far. I haven’t tried a free ride though.
If you want to try an air seat, I would recommend the KH, despite it’s deservedly bad rep. The parts are high quality, and the cover can be removed and replaced many times. The cover on the nimbus is stapled on, and an air seat has a sort of indeterminate volume. It is not a good match for a stapled seat cover.
I have never tried it, but perhaps you could buy the kh seat cover, and an inner tube (the kh bladder is an inner tube), and use that if you are a bit short on $. I don’t see the value in losing a nimbus seat though. I think you are better off buying the kh air, and messing with that until it suits you. Just be aware that few people are impressed with them stock.
My modded seat has gone about 1000 miles in the last 6 months. It is much better then the nimbus. About twice the sit time before I feel like taking a walk break. It is slowly getting a little misshapen, I may have to remove the cover and re tape it any month now. I will experiment then with a different type of foam, just for fun.