I have the Tech Air 5 and the A* Yuagara jacket. Fits well under the jacket and although it does have a significant weight to it, you don't really notice after awhile.
I did have a false deployment when saying my good byes to some riding buddies at the end of a ride. It was just a bro hug at that last stop at a gas station and boom, it deployed. Totally scared the sh!t out of me. Felt like someone came up from behind and slammed his hands on both shoulders.
After realizing what happened we started laughing. It took about 5 minutes for the vest to fully deflate and by itself in the non deployed state the vest is rated as a CE1 back protector.
Contacted A*s and explained what happened. Also read online of other false deployments. They acknowledged that they needed to update the firmware and asked that I send it in.
I was waived the $180 repacking fee but now I only have 2 more deployments on this vest before it has to be retired.
With regards to air flow, it doesn't flow much but I've had it on with the Yuagara jacket in 90+ days and as long as you are moving it is not that bad.
The Yuagara jacket has A*'s Drystar tech for waterproofing vs the Revenant which is Gore-tex. The Yaugara's collar is a bit high and can bite into your neck, but that is subjective based on each individual.
If you want to see if any of your existing jackets have space for the airbag to deploy, you can maybe go to SF Moto, ask nicely, and try on their demo vest and have them inflate it with their compressor.
The A*'s Tech 5 vest's charge lasts quite awhile when not in use. Just remember to make it a habit charge the night before. You can do some basic changes using the Tech Air app like change from Street mode to Track as well as update the firmware.
One con, and this is a nitpick, is that it does not have the plugs to interface with the Tech Air compatible jackets that shows the LED status on the sleeves.
I'm trying to get all my other riding buddies to get a vest as well, but everyone has already invested in their existing gear and don't want to drop another $1000-$1500 on a new vest/jacket combo.
At one point the Street dropped to $349 on Revzilla/Cycle Gear and I'm kicking myself for not grabbing one.
Good luck on getting your vest Bud.