I don't use insulated bottles and won't for one simple reason: the cold water (or whatever). I need a of fluids on hot days. I also find warm fluids don't quench my thirst like cold ones do, so I have to drink again soon. And again. I might even drink enough to stay hydrated. I can drink half a standard WB of warm fluids in one swig. And those warm fluids (if chosen wisely) are absorbed quickly in my stomach.

Then there is the fact that uninsulated bottles hold a lot more. I need that.

Ben