There are 2 methods by which you can integrate a different payment gateway other than PayPal into Vantage, this would be either by way of a plugin available from the
AppThemes marketplace, currently available are 2checkout, Authorize.net and Stripe. Outside of this, it would require some development, for which we do have some documentation available:
Payment gateways .
The Demo sites are fully functional, however data cannot be saved to them. You should be able to get some idea of the process, but if there is something specific about it you are interested in, please let us know. Thanks.