You're totally right that it's not necessarily a straight forward space. Constraining any complicated job (and websites are actually quite complicated) into a space where data entry is a hassle, fine tune controls are difficult, and it's hard to see the output at the same time as doing the creation task ... eek!
That said, I'm excited about the direction the app has taken as it has good potential for simply UX.
The other company in the space that's doing a neat job (and not in your list) is Universe! They've also got a really novel take on things.
Anyhow, thanks again for giving it a whirl!!