I have one!
As a cooler, the one I have seems to work pretty well. Though, I've never had a cooler before this one so I'm not sure how a fancy cooler would hold up.
As far as an under blanket liner-deal, not a fan. The neck hole on mine stretches a bit and gets stuck behind my mare's (low) withers. I can't imagine what it would do to a high withered horse!
It's ok for a few hours to dry a wet horse off, plus blanket, but it starts slipping back after about hour 2.
The fleece is also not the highest quality, mine has started looking like it has hair instead of fleece, after about the second washing. It still wicks well, just looks...interesting.
Fabio - 13 year old Arabian/Lipizzan gelding
Hazel - 14 year old Angora goat
Atticus - 4 year old LaMancha/Alpine cross goat
Rest peacefully, Lacey.