I just found this thread by "googling" the same problem - I just got a new Superlight (same design as the Juliana) and found the "small" size only has room for the bottle at the VERY bottom I really don't want to use a hydration pack if I don't have to. Also, I like to take liquids other than water, which I understand you can't use in the hydration pack. I am interested in that behind-the-seat bottle holder if it comes in a small, single-bottle version, as the dual type would prevent adequate "clearance" to descend properly (as someone already mentioned). Hmmm . . .

Happy but Thirsty