What is it that you are A/B testing with such a low level (I assume, the blog post doesn't seem to state an actual number) of current users? Are these really a

What is it that you are A/B testing with such a low level (I assume, the blog post doesn't seem to state an actual number) of current users? Are these really accurate experiments of the signup process if your only visitors are ones who actively asked for an invite or were referred?