I live in Miami and fly in and out of MIA and FLL regularly with my equip. I also fly for the airlines. Carry your expensive equip with you (reg, computer, etc...). Pack your backplate. You may be able to get it on, but it will draw attention at the x-ray. TSA isn't perfect, and while one may let you by, another won't. If you do pack it to carry-on, take it out of your bag and put it in a tray to send through the x-ray. You do this for the same reason you take your laptop out. The dense metal blocks other things in your bag and makes them nervous. Being up front will get you a long way with TSA. If they don't let you take it on because they think you will use it as a blunt weapon (I doubt this will happen since a laptop could be too), you will have a problem rechecking since your checked bags will be gone by the time you get back to the ticket counter.
If in doubt, call in advance. They see scuba equip everyday.
BTW, locks are looked at now as a guarrentee for a search. Unlocked get scanned, but not neccessarily searched.