I finally got to press my Texas Cool Vest into service on the way home from work. 50 minutes of 97F, 75% humidity on the Houston freeways to get home. It seems to work great. I wasn't exactly "cool" but when I arrived home I wasn't sweating and my hair was still dry inside my helmet. An absolute first for summertime Houston riding. No dehydration concerns as I started sweating within moments of taking off the vest while putting all my gear away. During the ride, I could feel that my hands and feet were hot but the rest of me was comfortable-ish. Sort of the same theory as an electric vest, keep the core temp at the right temp and the extremities will be OK. It has to be chinced up fairly tight against your skin (shirt) as the major cooling effect is from conduction, not convection (evaporation). One nice thing is that it works better without an air draft so I zip my 'Stitch all the way up. Probably wouldn't work too well with mesh gear. It's made from denim so you could probably be downright chilly if you poured some water down your back before setting off. Also looks like it will only work for about 1 1/2 hours so LDR stuff is out. Unless you keep extra packs in a trunk cooler or something.
A couple of minor drawbacks:
It's heavy, probably 6 pounds or so
I'd hate to fall off the first 20 minutes or so, until the frozen stuff starts to soften up. Ice is pretty hard, even if it's not made of water. Definitely getting a long over due back brace for the suit.
A bit expensive at $165 but considering I can wear it inside my full 'Stitch, I don't have to buy a second set of hot weather mesh gear.
I think it's the way to go for us poor souls that have to endure Southern summers to ride in.
I'm staying out of the ATGATT discussion except to say that, here in Texas, we don't have any laws about what you can and can not put in the back of your pick up truck. So we put anything and everything in there and it may or may not fall out. So I get a real graphic example on a fairly regular basis of what will happen when not wearing full gear, every time a dog jumps out of the back of some idiots truck at 50 MPH on the freeway. Yeech!