Love my GSP, but a word of caution..... if it's not kept in check, it will overrun your tank (and other corals). I just got done talking to someone else about this very thing... Below are two pics two months apart of my neon GSP, and if you notice, it's on it's very own rock away from everything else. That way it doesn't spread to the rest of my system.... I can pull out that rock & trim it without having to tear apart my tank.
First pic is the day after I brought it home, and the second is just a couple days ago. It takes a while to get going, but the bigger it gets, the faster it spreads.....