Replying to a few questions at once - yours first:
I know this gets old, but it's very athlete dependent. The campers can chime with their individual results, but the Torpedo works on a broad range of riders and, unless I'm mistaken, was the best overall bta setup - some found a regular bottle faster, others the whole system. Campers, am I wrong that no matter what the BTA bottle, it was an XLab mount?
For hydration, it's more than just aerodynamics (gasp!), which is why I like the Torpedo even more as a system with it's adjustability and ease of use. Love the computer mount up front for both visibility and because it hides behind your hands. There was one test with a computer mounted on top of the bottle and that wasn't a good performer. Of course, that all depends on how high the bottle is sitting above the extensions, too. In other words, if you're going to have a setup like that, you should work on getting that bottle low so the computer isn't sticking up above your arms.
Surprisingly, no one brought a Castelli T-1.
Downtube bottle placement is not only dependent on the frame, but also the rider. Very difficult to predict.
Andy, it's even more true now than ever before that speed doesn't matter for anyone who wants to take advantage of aero testing - heck Desert Dude's power meter has been lying to him for who knows how long, so he's much slower than he thought! :-)
Jim Manton / ERO Sports
Aero Tidbits posted on Instagram