Key scaling issue is pricing. 2.9% is fine for low volumes and no risk validation, but once you're turning over large volumes and have a track record of no chargebacks etc the comparison looks much worse. If you can offer businesses a pricing that 'scales' with substantial reductions in transaction fee by volume then there is a growth path, otherwise any business would be crazy to stick with you no matter how good your service and APIs, etc because 2.9% could be half their gross margin and they can get 1% by dealing with the bank direct.