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?
I assume you mean "Inorganic Marketing" versus "Organic Marketing" than inorganic growth. While, organic marketing is always a right way to move forward for any startup, it shouldn't stop you from adopting inorganic means as well. If testing is all that justifies the intent then you should stick to the organic means to do the same. Test, Measure, and Iterate to build a better version and then chose inorganic methodology to attract people.
Inorganic may be tempting at times but, you should try to visualize beyond gory numbers. More "Like" doesn't means more customers.