Glad to see you back, Drippy. Get in touch if you need anything.
My advice ... your new PGP key shouldn't cause any problems - just be sure to provide it each time and if it's for a vendor you've used before, then just let them know you have a new key. It shouldn't be an issue though because plenty of people end up needing new keys for one reason or another.
You may *want* to start a new account for the sake of simplicity since I don't think there's anything that can be done about your refund rate, and just as an additional security measure. Totally up to you though.