First of all, if a bike shop tells you that you can run a 1x9 without some sort of chain guide, turn around and take your business elsewhere because they don't know what they are talking about.
There is nothing worse, nothing more confidence sucking than a chain that drops off at seemingly the worse possible moment - sending your knee lurching violently forward into your stem or bars.
Fritz had an extra "dog fang" that he let me use. To be honest, I only got a handful of rides with it. It was MUCH better than the original set up, but I did have issues with the chain hoping up on it. The chain did fall between the plastic 'fang' and chain ring once. It is made of a plumbers pipe clamp and a plastic piece. It seems like it could wear over time.
Like I said, this looks like it's the dealie-o! Will give a thorough review, maybe even 'naked', in the not so distant future (once the trails dry out!).