Agreed, JohnK is the best escrow, but there are also a lot of other possible escrow providers with various ups and downs. Also, keep in mind escrow with paypal is kind of pointless (paypal can be charged back unless the escrow is 45 days)
Chargebacks can happen even later than that with PayPal... There's some real horror stories out there.
I'm fairly sure chargebacks can be back as far as 6 months.