In hot weather they are all moving sweat boxes...
They all make more noise than soft fabric... Patagonia are the worst in that regard IME... Simms are the best. I would forget about the camo thing.
Filson makes waxed cotton chaps which, once broken in, will be much quieter in the brush. They will also protect your very expensive waders from the brush.
You get more layers of fabric as you move up in expense, but if you are only going to use them once you can forget about buying the very best. Cheap ones will not survive a week of heavy brush-busting... and that can be as little as climbing up to the look-out point each day.
