flagamuffin is correct: invite systems work where there is incentive to get behind the wall. With Facebook it was exclusivity. With Gmail it was functionality. With trackers it's content. With Hubski it's... what?

This is a solution looking for a problem. You end up with Google Glass this way.

It seems like the real question is "Who does Hubski want to attract?" and "invites" are suggested on the presumption that current users will be better able to affect that answer positively than Google will. However, there's nothing quite so silly as an invite-only club that offers zero benefits to its members.

The real real question is What does Hubski want to be? and I get the real sense that Team Hubski is attempting to answer this question iteratively.

Look at Hubski 3 years ago. Look at Hubski now. Project forward 3 years - do you like what you see? Great. Leave it alone. Do you notice some disturbing trends? 'K, brainstorm about how to address that. Do you sense an opportunity for improvement or expansion? Great. Maximize that.

There are cool tools in the world. I don't own a lot of them because I don't need them. Going invite-only seems a lot like buying a tool and then trying to find something to fix with it. Great fun for the handyman but everyone else has to deal with their leaky pipes being repaired with an air nailer.