I think the Quora example does give off a bad vibe. a) We are a Quora for the enterprise b) We are Youtube for audio Quora for the enterprise sounds like a superset. Quora, plus enterprisey features. Quora could compete, their core competency is in that set. Youtube for audio sounds like disjoint sets. OK, I know what Youtube does. They do video well. I could see a good audio site that does it similarly, allows user…
Portraying your idea as the sum of several individual models can be a very effective technique. Saying something like "you can send your friends fake gifts, just like you can on Facebook" and "you have a live chat window like JustinTV" is more likely to promote understanding and less likely to raise questions than saying "Imagine if Facebook was better..."
(Yesterday, I actually saw a presenter get grilled for 20 minutes about features completely unrelated to their program, due largely to the fact that they took this "Imagine If.." approach.)