I am actually drinking one of them right now. Bought two of them at my local stupidmarket (Safeway) on Friday and am going to stash away one of them along with the Zappa tribute beer I purcahsed last year. Overall I like the hoppiness--Lagunitas never disappoints in the hoppiness department, and I've always loved Frank Zappa. Cheers to you, Frank!!!
"Evidently, the setup adds some weight: about 12 lbs more than a regular wheel" -- which means that you'll be too tired at all to use traditional means (the pedals/cranks) to power the bike anyhow, so it sort of defeats the purpose.
"On a flat surface, the engine will even take you up to speeds of 20mph, with a merciful 200mpg." -- on a flat surface on my road bike I regularly average 28MPH, so other than fatties and generally people who are out of shape, I cannot see this as something that appeals to the semi-serious cyclist.