Releasing a social app in the coming weeks which utilizes Network Effects and Groups of Friends. For the Beta, we have identified specific groups of friends we want to test the app on. However, should we limit their individual ability to invite friends to join the app?
For Alpha / testing round - yes. For a Beta - absolutely not.
If you get lucky and your app 'goes viral' then this is a good problem to have. Odds are that you will able to sort out any issues relatively quickly, whereas artificially limiting growth would potentially result in losing out on a lot.
As Reid Hoffman famously put it - "If you are not embarrassed by the first version of your product, you've launched too late."