I ordered and received a TekVest a couple of weeks ago, and finally got to get a decent ride in it today (several hours, in the heat).
I went with the Freestyle model...it's their "entry" level vest. I chose it because it had the ability to add optional removable arm guards (they're fixed on the Rally vest above), didn't have extraneous pockets, and was front entry. The front zipper entry give up about an inch of protection in the front, but allows easier on/off and allows you to partially unzip and get extra air flow.
I'm very susceptible to heat and was worried about overall heat management. I did about 4 hours of dual sport riding today...highway/backroads to the playground in Fultondale, a couple hours knocking around on the powerlines and double track, and then back home. While I did get warm, it was never any worse than if I had been wearing a normal chest protector. It feels about like when I'm wearing body armor at work.
Size-wise, I wound up ordering a Large. I'm 5'10"/212 lbs. and normally wear an XL in t-shirts, jackets, etc. I emailed TekVest to inquire about sizing, and they suggested I go with a Large. I'm glad I did...with just a wicking t-shirt underneath, I had the adjustment straps let out with about an inch of strap left and it fit great (just a little loose to let air circulate). I've tried it on over my dual sport jacket to see how it will fit in cooler months, and with the straps all the way out it's spot on. I think with an XL, I would have had the adjuster straps cinched all the way in with a lot of extra strap flapping around. If the straps worked themselves loose during a ride the vest would be much too floppy and probably not provide optimal protection in a crash.
Material and construction quality are first rate.
For now, the airbag vest will have to wait.