That's not quite what I meant. Velour does not seal air as well as leather therefore air can move more freely in and out. Now usually people look for pads for improved comfort. If you change the material, the sound signature will be altered.
Velour on it's own eats up bass, but these have memory foam which will have a bigger effect than the velour outer layer. I think the hybrid ones are the way to go, you'll get additional seal around the already sealing memory foam while also getting the benefits of the velour (no heat and softer)