I am considering to use AbanteCart but I kind off have the same problem.
For a E-commerce shoppingcart system to work in my country I need the payment option "IDeal". Since I am not that good at making extensions I would like to receive some help or documentation how to make a payment extension!
From what I have seen I really love AbanteCart, but this is a must for The Netherlands. I think it you guys should consider adding a "IDeal" provider as payment option. E-commerce is pretty big in The Netherlands. I am willing to help a developer!