Do customer payments sync to Xero?

Yes, once you pick a bank account for payments in the Xero account mapping; it must be a Xero account of type BANK. Each new payment recorded in BytePhase is sent to Xero against its invoice, and an invoice that has not gone across yet is sent first. Leave the bank account blank to skip payment sync entirely. Editing or deleting a payment in BytePhase after it has synced does not update it in Xero.