We do need gateway options, each country is different and we're always being asked by users for support of X. I can promise you if we'd been able to stick only Stripe in and use it for everyone, we'd of done it. Our lives would have been so much easier!
And no we wouldn't call it 5% but the store owner would quickly do the math and that's where we'd end up. It's a hard sell, we ran the model past a number of people and it was almost universally rejected.