Dwolla isn't ideal - but it's a big and growing company that's built 100% on a foundation of "try to get people to pay with Dwolla even though it's hard just to save the 3%". Things that save that 3% and can serve the entire market or a bigger percentage of it more easily* have a chance to equal or surpass Stripe's growth because of how interested businesses are in this.

*disclosure: I run such a company