Perhaps if we were accepting pre-orders or requiring a credit card. A soft launch like this would be more comparable to a focus group for a traditional product launch.
If it was like "Click here to take a survey about what features you most want in an email service" that would be one thing, but that's not the messaging in your case.
Focus groups et al. are consensual. This is deceptive.
"Yellow Walkman" story is appropriate http://www.alexandercowan.com/yellow-walkman-data-art-of-cus...
"The moral of the story is that you need natural behavior for quality observational learning."