Aerobar horizontal water bottle question

I've just read this article on water bottle placement:

http://cervelo.com/en_us/news-blog/article/ask-the-engineers-hydration-and-aerodynamics/2930

Interesting read.  One of the conclusions is that a horizontal bottle between the aerobars can actually reduce drag.  I've been using an aerobottle, but this has tempted me to change my setup.

So here's my question: the bottles handed up at Ironman aid stations are the squishy kind you find in a grocery store, and it doesn't seem like they'd stay firmly in a horizontal bottle cage.  Has anyone tried this?  What cage did you use?