It can be more, depending on the plate. They make softplates, plastic plates, aluminum, steel, you name it. I have a BPW that I made that weighs 5 lb total, others have stacked steel plates that weigh 13 + for the plates alone... and everything in between.So the wing/backplate = more weight.
You keep mentioning not DM-ing anymore... BPW is just a different BCD, no more, no less. Nothing to do with pro or amateur, frequent or vacation diver. In your shoes, I'd try one (borrowed or rented) to see how they dive. Some love them (me and both my boys), some prefer jacket BCDs (my wife). If your anywhere near the scuba ranch in texas the 20-21st (next week) I'll be there with some vintage stuff and a couple BPWs... you're welcome to try one out.
Respectfully,
James