I've had a lot of questions about why I am running this through my store versus X. The short answer is that I keep updating the product, and the easiest way to send out those updates is through the digital library backend I built.
Why a Digital Library instead of a link?
I built a digital library to house the master copy of my manuscripts. This means all of my backers spread across multiple crowdfunding campaigns, customers, and people trying out my free products only need to go to one place. They know they are getting the latest and greatest version of the product. In practice, this has allowed me to update the product from the original 61 pages, to 110 pages, to the current 200 pages and most importantly notify everyone who picked it up that new content has been added. If I did a link, I'd have no way to tell people the latest release is out.
Why not DMSGuild?
You give DMSGuild the exclusive right to sell your product. They take a 50% cut. I'm not interested in either of these things. They used to not allow your own settings either, I don't know if this is still the case.