Absolutely love Sparkle and the latest 4.0 release.
The written documentation is good and succinct, but could benefit from a series of related short video tutorials (3-8 minutes in length) to explain each feature and typical design / publishing task. Host them both on the sparkleapp.com domain and on your YouTube channel.
I sure would appreciate such a collection of tutorial videos, and I would think that they would further help make the sale with prospective buyers.
For a great model, take a look at the video tutorials for Serif’s Affinity Photo: Affinity Photo for desktop tutorials
Thanks for your consideration.