The idea is excellent, although I would miss the versatility of the Nalgene bottle with cup.

I'd want to handle one before I would trust it.

Off the top of my head:
- Is the bottom thick enough to withstand some abuse?
- How well-formed are the threads (pressed or machined)?
- Are the threads compatible with Nalgene lids (for screw-on water filters)?
- Does the top reliably seal? Many cheap bottles look good, but leak.
- Can the top be removed entirely (for cooking)?
- Is there a way to attach some wire for over-the-fire use? The Sigg bottles have a neck that's perfect for this.

If someone buys one, a field review and close-up photos would be appreciated.