Cool idea. I wouldn't mind spending the $50 for the device, but the $13 a year stuff is where I lose interest.
Personally, I keep all my dive gear in my carry on: regs, computer, mask fins, wetsuit and my wife packs my BCD in her carry on.. it is a tight fit. I just don't trust the airline workers, because I'm afraid they will misplace it or steal it. I can always buy more clothes in Cozumel if they lose/steal my checked bag, but I would be ticked to have to trust my life to used rental equipment.
Your fins fit in your carry on? They've been checking carry in sizes in Canada pretty closely......mine won't fit.