Well, I got lucky. I've had my scooter blenny now for about six weeks, and he's doing great. He's actually grown, and his stomach has filled out quite nicely. I've only got a 40g tank, but I have over 80 pounds of live rock. (Also have a refugium with a good supply of amphipods and copepods).
The reason I say I got lucky is that my scooter blenny actually eats Formula Two pellets! I threw some in there for the peppermint shrimp one day (they love them), and much to my surprise, "Scooter" came out of nowhere and devoured most of what I put in.
His diet now consists of copepods, amphipods, live brine shrimp and Formula Two pellets, and he's king of the tank. (He's only got two false percs for company).