Looking at moving our Paid hotspot platform to RouterOS

Hey all, I have been using a mashup DD-wrt solution for providing paid hotspot access and looking at trying RouterOS with our latest client. What payment methods exist for clients to purchase time? I have been looking at the 600 model as the core hardware, is this correct for what I require? My main reason for moving from DD-WRT is the hardware limitations .. anyone been down this road before?

Any and all comments appreciated!

RouterOS has the User Manager solution which supports payments with Paypal and Authorize.net

lol, spam much?