Maybe be ready to be flexible on this - I've noticed that Scouts will all adopt the hydration bladder if they have one, and sip from the tube all day on the trail. And why not - a hydrated Scout is a happy Scout.

For the Nalgene bottles, there's also a 1 liter soft-sided variant put out by Nalgene and by Platypus that I mostly like - except they tend to slide out of the pack pockets unless you strap them down. Also in this line are larger 3-4 liter soft-sided nalgenes that are great to have when you get to a campsite and want to filter a bunch of water. With the soft-sided bottles you get best of both worlds, clear sided container that weigh less empty. I don't put much stock in the water filter compatibility - not very hard to get water in a nalgene bottle, or soft-sided bottle, or a hydration bladder.