Doesn’t anyone go with the Profile Aero bottle up front? or is Jetstream so much better? If it is - Why?
Personaly I plan on duplicating Pooks strategy (Minoura with Profile cages) but I was planning on using the Aero bottle.
I thoroughly enjoy my Profile Auqa Rack used with 20 (24?) oz Specialized bottles from Jamba Juice, $2.50 ea. and have never launched a bottle, even on some seriously bone-jarring courses. I use the bottles from the Aqua Rack to refill my areo Drink. My bike only has one set of braze-ons and even using a Profile Aero Drink, I was Jonesing for more of MY drink on long training rides and races. The water along my training trail is nasty and I dislike the Gatorade at races. I’ve never had any handling concerns regarding a full Aero Drink. Perhaps I’m not knowledgable enough to know the difference, but I’ve never, ever felt squirrelly. Ignorance is bliss. The Profile Aqua Rack also doesn’t create a dismount problem as it sits low on my seatpost.
Also, I’ve always enjoyed seeing bottles strewn along the race course just knowing they got launched. I saw one bottle launch at Wildflower Oly last year. Quite a site and humorous, too. I’ve never crashed due to a launched bottle, so forgive me if you’ve had a negative experience. I know they’re dangerous, but it adds to the challenge and humor of the race. 
Xlab saddlewing with a custom tube drinking system for olympic and saddlewing with Profile Jestream for longer races. Forget the Xlab Aerowing, it’s heavier and sits to high. Aquarack weighs a ton. Anyways that’s my setup. Although I haven’t yet figured out how to mount my Jetsream on my new HED bars. I’ll have to try that new bracket Profile is selling or just make my own. Or I could get REALLY REALLY BIG bottles and use my aero tube thingy… yeah the bottles would have to be huge
I agree that behind the seat bottles suck. I have a Profile Aqua Rack with Profile carbon cages and cannot keep bottles in the cages for more than 20 miles. Any real pothole, speedbump, or sudden acceleration will shake the bottles free.
I took the rack off and it is sitting in a pile of useless cycling gear. I did reuse the cages as they are pretty good.
On training rides I just put the extra bottles in my jersey pockets. When I race long tris I use a Profile handlebar mounted drinking system that works pretty well.
A roommate of mine has the Xlab system with aluminum cages and he seems to keep his bottles. I wonder if there is something in the XLab design that results in better retention? Can anyone comment on the physics involved with this issue?