That's a good note indeed, Walt!
We do not support recurring billing for PayPal Express I believe.
The reason PayPal Express button is displayed is a requirement from PayPal to have that button displayed at all times a merchant uses PayPal in X-Cart. This is their condition to have our PayPal integration approved officially.
Also, they have something in their merchant agreement about that.
See
http://forum.x-cart.com/showpost.php?p=371816&postcount=58