Hi Steve and Michael,
Indeed you need to upgrade to X-Payments 2.1.1 and re-deploy X-Payments configuration bundle (re-import of payment methods will happen automatically) when you upgrade an existing X-Cart installation connected to X-Payments to 4.6.4.
We will correct our posts to reflect that.
Also, the new connector works with older X-Payments versions, too, but many of the usability improvements will take place with X-Payments 2.1.1 because changes have been made on two sides - in X-Cart and in X-Payments. Since changes in X-Payments assume releasing new versions we released 2.1.1, but unlike for X-Cart we can't release "adapted" versions of changes for older X-Payments
For older X-Cart versions we are preparing updated X-Payments connector modules that supports everything we've implemented in 4.6.4 and they will support 2.1.1 fully, of course.