Hydration systems definitely are the way to go. Whether in a pack or on your back, a hydration system (Camelback, Hydrastorm, Source) are easier to access, keep the liquid cooler (or warmer as the case may be), and more comfortable than canteens. Hydration systems also are probably quieter than canteens, since there's no sloshing around of fluid.

I've had canteens and I've had hydration systems and I'll stick with the system!

Best Regards,

atty_guy