The OP says he "Only sells to people with significant positive feedback", "Only ships to CONFIRMED Paypal addresses", and "Requires Signature Confirmation for items over $250" Does ebay policy allow this? I thought the seller had to sell to the winning bidder, regardless of buyer's feedback, etc.
Confirmed address is a paypal policy you can also turn on, which forces the seller to use their paypal confirmed address when checking out or none at all. If someone wins and they ask you to ship elsewhere, you say no. Which sucks because the buyer might ding your DSRs (detailed seller ratings), which determine your ebay privileges, search ranking position, fees...
(Whoever decided that buyers should be exempt from negative feedback needs their fucking head examined)
Signature confirmation is an option you set with your shipper.