I'm trying to set up an on-line payment system for a website and someone has recommended Roman Cart. Does anyone have any experience of this? As far as I can see from their website, you have to sign up with them as well as a 'payment gateway' such as Paypal or Nochex.

So what's the advantage in using them at all? Why not just use for example Paypal? Any advice on other systems?

Thanks very much!