I used elastic to hold my shoulder bells, doesn't seem to be an issue with pulling, but then my biceps and forearms are just touching so don't pull.
Elastic is strong enough for your chest/ab so on, helps when you are moving, I did try nylon on another build and it's not as easy to move, in my opinion.
I haven't had to replace any elastic as yet, all has stayed pretty much the same as 5 years ago.