I wouldn't accept PayPal payments from people who don't have any or low trust here. It's a classic scam that's happened many times: buyer gets the bitcoins, and then files a chargeback with PayPal. Doesn't matter if it's paid through Goods and Services or Friends and Family. Lots of people seem to think that F&F payments aren't reversible, but I've heard of F&F transfers being reversed after the sender claims that their account was hacked.
Well you can open a conflict and close it again.
Once closed It's not possible to open a conflict again tho.
EDIT: The buyer have to do so
That is a lie. It can be opened again with a phone call to Paypal. It's been done before MANY times.
Was going to mention this as well. It might be a little harder to open a dispute a second time but it's very doable.