@Uncle Phil began a thread about vests. If it is still on the website after the Great Deluge, read it. Bottom line is airbag vests save lives. I wear one and a few months after getting my Turtle 2 (tethered to bike) I left the house without it. By the end of the driveway I felt very uncomfortable without it, stopped and ran back to get it.
Yes, they can be a little warm. I unsnap the top buckle for a bit more air flow. I either wear a RoadCrafter Stitch jacket or a Klim mesh jacket under the vest. Bulky? There have been studies that show that heavy blankets make people feel more secure when going to bed. Crazy as it sounds, my Turtle 2 makes me feel protected.
Advantages are mostly listed on their websites. A standalone vest like my Turtle 2 can be worn over any other mc jacket. An inflatable jacket/vest is a one piece unit. My vest is self packing after deflating, some brands require you to ship the unit back to the factory for inspection/repacking. Tethered vests (my Turtle 2) allegedly deploy slower than the electronic sensor types but have batteries that must be charged. Some brands require a subscription - a practice that I liken to profits over your safety. You will have to do your own research and decide what you like. My feeling is no piece of PPE will cover every situation. Any of these inflatable vests will protect you more than not wearing one, and I hope mine performs as well as Phil's if I ever need it.
All of the vests are reusable but some require shipment back to the factory for inspection. Some (like the Turtle 2) can be put back into use after your quick inspection for damage/tears and a new CO2 cartridge - maybe 5 minutes or less. It will be best if you do as much reading as you can about these things and then factor in what guys who you know (on this website) say about their experience with them. My 100ml cartridges cost me around $40 each time I 'tested' the vest (dropping your bike constitutes a test).
One caution. If you do buy a vest, make sure you adjust the straps properly. Read the instructions! The first time I 'tested' mine, it was uncomfortably tight. Somebody who did the same with his complained about chest pain afterward (cracked rib or just bruising?).