Crossbreed BBs are kydex....
The problem with the elastic of belly bands, is that the top edge of them roll over.
The first rule of conceal carry is to not fiddle with your conceal carry.
Trying to push that top roll over back straight up, just to have it roll back over again would be the bane of your carrying existence. People will see you messing with it.
Elastic is rubber. Rubber doesn't breath. Sweating is miserable.
If you ever get the bug thinking you want a belly band, take a fresh crisp 50 dollar bill (that you would have spent on it) and place it in the dresser drawer where that band would have sat for a year. And then a year from then, you'll have a fresh, crisp 50 dollar bill to spend.