Just to re-iterate my point...with eCart you HAVE to complete a delivery address. You can't proceed to PayPal without doing so.
It doesn't make sense to me to then ignore what the user has entered at that stage and hope that the delivery address stored in their PayPal is the delivery address they wish to use for this particular order. I'm not understanding your reason for recommonding caution on that.
Also just to confirm that what I'm removing is on pp_confirm.php.
Won't removing that affect the eCart Store Summary to Database behaviour, which is currently storing the information sent from PayPal, not the information the user enters as their delivery address on the website?