I can see how they would be similar on the receiving end, but I don’t think they’d feel as similar on the user end.
Joining a beta feels like more of a commitment than reading a preview, and it’s a commitment based on a premise, not something more substantial, like a sample. And since you’re not supposed to join more betas until you’ve sent in feedback, it’s not as easy to see “oh, yes, this is a game I’d really like to test!” before taking the plunge. I could see a preview as a way to entice people in who might not otherwise try it out at all.
I realize that I am speaking for myself, inasmuch as previews like these would definitely draw me in… so that’s why I’m inquiring here, to see if anyone else would similarly find that previews would catch their interest more than blurbs.
Alternatively, if a preview is too much, perhaps just including a writing sample might help? 