About 5 years ago we replaced all the carpets in our house, we ripped all the Treadair out (green one that you have) and replaced with Cloud9 11mm on the recommendation of a carpet fitter friend who has been fitting 25 years. Best thing i ever did not had a single problem with it and it still feels as bouncy as the day it went down and retains heat great.
Rubber based underlays such as treadair don't stand up to spills and in my experience deteriorate to quickly.
Yeah we're going to have to agree to disagree mate - I'm sure we've all got our stories. If you think it's the best thing you ever did, well, we'll let others decide whether you say that in earnest.
btw my second carpet fitter for my house answered my complaint about the cloud 9 with the statement "Really? that's quite good - it usually flattens down before we've left the house" and no he wasn't my friend.
Underlay is like anything in this world - You get what you pay for and I have hands on experience with both types for over 2 years now. Sorry but I'm simply not one of these types that needs to be right on the internet. My opinion is based on direct experience take it or leave it.
Cloud 9 and dream walk is the same type they sell in carpetright with their customary, ridiculous, mark-up. But even their upper range goes into rubber waffle.
Let's get something straight all carpet and underlay flattens down - it's the amount that is all there is to debate.
The thread has moved into wool composite now which ALL carpet companies regard as the best type and for what it's worth IF I had known about Axminster Axfelt65 (Hands down the BEST underlay) I would have looked into that.
The only thing about wool is that, so i'm told, it's designed for wear and tear rather than comfort but I have no frame of reference.