Durability?? I have had the tower CG machine for 20 years and it's just plastic. Then again I don't throw it across the shop if I'm upset about something.
The CG is the CG and the wing type doesn't care if I'm using fingers or any other type. I have balanced several Bipes with combination wings.
I think I paid 12 or 15 bucks for the tower machine and it works as advertised too. Then again, so did the two pencils in a wood block. Think that one cost me 10 cents to make.