4.1.x branch added and all the connector modules have been updated, too.
Our official announcement of the new connectors has been published at
http://blog.x-cart.com/x-cart-4.x-connectors-for-xpayments-updated.html
Also, For PayPal users: If X-Payments payment form is not displayed for PayPal payment methods on checkout, try to disable and then re-enable "Use Iframe" setting in X-Payments connector module settings.