No issue at all adding the 5 cards that were in my old 6 Plus after Restoring from Backup. Apple Pay presented each previously stored card, asked for the CCV number, and activated them successfully. Three Amex cards, a Citibank Visa, and a Wells Fargo Debit card. My Apple Pay Cash card was automatically added with the correct balance.
I was a bit clumsy using Face ID with Apple Pay for the first time at an Apple store. Just had to move it away from my face. Purchased the green folio case for my Space Gray XS Max. I love how it works as a smart cover.