I think Paystr is the way to go. They are new, but they offer a bunch more. Yes, they take a bigger cut than gumroad, but they offer a ton of services for your digital downloads, like support to your customers, if they have an issue, they call Paystr and they will resolve it, you do nothing. Also, if you sell enough, you can get paid THE NEXT DAY. Check them out at https://www.paystr.com. If you want to see them in action, go to http://www.joshuasring.com and try to buy the book, that's the checkout process. I love how the customer never leaves the site.