so no air in the BC is something that can only be done under certain circumstances. Largely AL80 diving with no exposure protection. If you start diving locally in the mid-Atlantic, you won't be able to do that due to compression of the wetsuit. You can technically dive with no BC with thick wetsuits, but the weighting gets weird and it's not recommended. They did it way back when, but you have to have weighting set for different depth profiles, and it's generally annoying.
So, the pros and cons of a bp/w vs a jacket have little to nothing to do with the air cell itself in my opinion. The air cell advantages are nice, but not the "big one".
BP/W advantages:
Buoyancy: most jacket bc's float, and the bp/w will allow you to take between 6-10lbs off of your weight belt and if diving without any wetsuit with an AL80 in the Caribbean, you are likely not to need to wear any weight belt at all with a SS backplate. This is a huge benefit. I haven't worn a weight belt outside of skill demo's, ever....
In water stability: the bp/w has a nice large platform that the tank is able to use to prevent rocking. Jacket bc's use a narrow piece of plastic and the tank can rock around on your back unless the jacket is cinched way down, not so comfy.
Surface stability: Crotch strap... All bc's can have crotch straps, but most jackets require you to sew one on where bp/w's are designed for them. This and the waist strap are the most important straps on the rig while underwater, but also on the surface. To keep a jacket from riding up on your body, they have to use wide cummerbunds that are cinched tight with shoulder straps cinched down as well. With a bp/w the shoulder straps are quite loose and the waist strap is at your belt line. Waist strap is put on about the same tightness as the belt on your jeans, and when at the surface you basically sit on the crotch strap which has a similar sensation to sitting on a bike seat. Much more comfortable imho when at the surface since you are largely unencumbered.
Cost: the best bp/w on the market imho is just under $500. Most quality jacket bc's are at least that expensive if not more so
Durability/Modularity: If something critical on your jacket goes, you are resigned to chucking the thing. With a BP/W, if it gets cut off in an emergency, you are out a $20 piece of webbing. If the wing get's a puncture, you may have to spend $100 to replace the bladder. No damage can really "total" the rig. This modularity also allows it to be used in different scenarios as well. You have some of the best wreck diving in the world in your area, albeit with some conditions that leave a lot to be desired. If you purchase say a 20lb wing to be used on your Caribbean trips, you can purchase a larger single tank wing, or a doubles wing, and start doing the wreck diving in your area. Not a huge expense vs. potentially having to buy a different BCD.
The other huge part of their modularity is unlike jacket bc's where the lift is determined by your size *even a lot of back inflate bc's have at least 2 different lift capacities based on size*, you get to actually tailor the lift to your needs. I'm a big guy at 6'3", if I go to Scubapro and want to buy a bc, I will check out the Classic. In an XL which is the size that I need, there is 81lbs of lift in that jacket! Knighthawk has 45lbs and is a back inflate... I would be purchasing those rigs for warm water diving like you, where I'd be using an AL80, and assuming no exposure protection, but still want to keep my head above water, I need ~15lbs *for head*, plus ~6lbs for the air in the tank, so a 20lb wing is more than sufficient. The Knighthawk has me carrying double what I need, and the classic at 4x what I need. This is added weight on the rig, more area for the bladder to get damaged, more fabric to hold water and take longer to dry out, more drag when in the water, more places for air to get trapped where I can't easily dump it, etc. With a bp/w, I can take my long pattern plate from DSS, and put anything from a 12lb Super Scooter wing, all the way up to the 57lb Torus doubles wing depending on my needs. Same harness, same backplate, but the wings swap out and are fairly inexpensive.
Packability: because of the modularity, the rigs can be quickly and easily disassembled to allow for better packing dimensions when travelling. You can also leave the plate somewhere, and bring just the wing inside to clean out and dry out. Wings can be removed, rolled up like a towel and stuffed somewhere in your bag to keep them protected while the plates can act like a skid plate on the bottom or top of your travel bags.