I don't get your concerns? We do get upgrade when we become sellers. In fact, it has more protection for sellers especially when your buyers filed for a chargeback with credit card compnaies against you.
It happened to me a few months ago but it has protected me because I upgraded it to higher level at PayPal, otherwise I would lose $150.00 plus the items that I sold to the buyer when he claimed that his purchases was not authorized which was absurd and the credit card company later rejected his claim as it was suspicous as he filed for chargeback too often to suit his credit card company.
However, PayPal informed me that I am protected should it is a fact and wouldn't deduct $$ from me. You can call PayPal and ask them questions to make sure. It would hurt to call them.