1. Do not rely on another one to bail you out.Having the second depth reading wouldn't worry you for any situation where the computer fails and cannot give you depth? Or is this one of those situations where you would push reliance to your buddy to help safely finish the ascent?
They did not have any wing that I saw. They explained that people move to wing BCDs when they are seeking to either go for lightweight travel or have something specific moving them that direction.
2. Plan ahead. I dive with TWO entry level computers and also carry a SMB with spool. The line on the spool is permanently mark at 6 and 9m.
3. The shop does not sell BP/W so you should take any -ve comment with a large pinch of salt.
4. I have not seen any dive operator offering BP/W for rental/training except for tec dive. So most if not all beginner divers would have no knowledge on it.
5. Unfortunately buying the first BP/W is NOT that straight forward for a beginner. You really need a good guidance on the topic. There are a lot of posts on BP/W in SB so look it up.
If in doubt just come back and raise the question and you will receive plenty of good advice/suggestion etc etc.
Just do not rush out and buy by impulse.