"No messy onboarding required" - it means that your testers don't have to signup or login to send feedback. Their interface is purely email. You pose questions from our dashboard, they get sent an email secretly on the backend. When they reply to that email, it comes back into their feed (which is the third benefit).

Think of it as if you wanted each user to use Posterous to send feedback, except their blog is already private, and they just reply to an email prompt from you to post to it.

Does that make more sense and seem valuable? How might you rephrase the last 2 benefits to make it more clear?