Any question answered...

Do I have really weak fingers, pro riders have really strong fingers or do pro teams have bidons that are much softer and more flexible than any that I've come across?

You see them effortlessly squeeze the shit out of them when they're drinking, but the bodies of all mine (mostly Elite Hygiene) are way too stiff to really do that (may also have too small an opening to allow a high enough flow rate, but I don't think the bottles would flex like that even with the lid off).

Late to the charge here....
I've always known Elite bottles to be too stiff. Not just your weak fingers. SiS and Hi5 are great though.