I have had one in my tank for 5+ months. The only issue you run into is when you clean the glass and hit his spines. He is mostly on the glass or back of the tank and is never really on the rock, i have more issues with my hermits knocking stuff over, he hasn't messed with anything.
So my vote is throw one in your RSM!
Edited by Holyzion - December 20 2012 at 3:03pm