Loving the 600ml version so much that I've stopped using all my hydration bladders!
For tours when I need more capacity, I just bring a reserve collapsible bottle in my pack.
A few issues to be aware of though:
- The thread closure for the cap could be improved. Even once you've correctly tightened it (and not started to cross thread it), tighten it again, then invert, so as to ensure it really is tight enough with no leaks. (For unscrewing a very tight cap after the tour, I've found blowing back some air...