Speaking of Nudibranchs in general, it appears that Sprung agrees with Adam.  Coral eaters are Reef Safe.  On page 94 of Invertibrates a Quick Reference Guide under Phyllodesmium Desirable/undesirable features it says "Ornamental, Destructive or harmful to corals.  Reef Safe."  Sounds like an answer Adam would give.  As long as it doesn't hurt algae, let it be.

By the way Phyllodesmium is the one Nudi that Sprung says can do well in Aquariums.  He says they can live years and even propogate.  Problem is they eat soft corals.

Sprung's Invertibrate book says...Feeds on sponges.  Life span weeks to months.  They can live for several months in an aquarium and this is a significant portion of their natural life span. 

So if you can keep it for 4 to 6 months thats actually pretty good.  They don't live much longer in the wild.

I had this guy come in on some rock. He lived in the tank for 4 months before I caught him munching my blue sponge. --> This pic is him in a jar.

Here is a link to the picture of the nudibranch they had to offer, its scientific name is Chromodoris bullocki

  http://www.thinbluelinesafari.com/DTM04070501U/pages/Nudibra nch_Chromodoris_bullocki_03.htm

I've had mine for 4 months and it's still kicking!