Good anecdotes, but whether people use Groupon isn't really in question (this question typically gets resolved when companies do their A round, not their G roun

Good anecdotes, but whether people use Groupon isn't really in question (this question typically gets resolved when companies do their A round, not their G round). The question with Groupon is whether their model is defensible; that is to say, is it possible for 100 competitors to spring up and chip away at their business (or would it be possible for Google, eBay, or another BigCo to leverage their existing users to take a large chunk of their business in a short time).