D'oh, yeah I messed up the numbers. What I meant was of course 10, 20 or 40 mm 
I'm pretty sure the 10 mm can be ruled out at this point, but based on what you are saying I will properbly go for the 40 mm version 
I don't think you will regret going with the thicker.
The seat on my build is kind of a sore spot for me. I had an upholsterer volunteer to do a sponsored seat for me when he heard I was looking to redo mine. My old one was just 2" gray vinyl and cost me $50.
I gave the new guy 5 criteria for my seat and when I got it back from him almost 2 months later, while the build quality was very good, 4 of the 5 criteria were wrong. He refused to redo it for free. I told him it was unacceptable for my application. He told me I could burn it or throw it in the trash. It let such a sour taste in my mouth I even changed the whole color scheme of the bike because of it.
I told him I would pay to have one done by him if he wouldn't redo it free. That's when he told the first one would have been $750, he said the embroidery alone was $250 (I had the new embroidery done for $6). I think the last thing he heard on the phone was me laughing at him.
I found a new place to do a sponsored seat for me and I like it a bunch more than the old and black seat. One of the criteria being I wanted only 1" foam this time and though the new one is only about 3/4" I like it, but the first time I sat on it I realized it is going to be very uncomfortable and hard.
