PAD is between you and Paypal. The seller is unaware you are using it as they are still credited the funds in advance. No seller would post an item before being paid. Funds leave your account at 14 days in which time your item 'may and normally has' arrived however you don't actually have anymore 'buyer protection' than any other buyer. Its basically a 14 days interest free loan provided by Paypal. BUT its not offered on every transaction and you can only use it when it is, I guess thats down to paypals cash flow status at the time of your transaction maybe?
Advice is voluntary. Kudos / Solution appreciated.