Good question. I added 5 a few weeks ago and have not seen any of them until I spied 1 this morning. He may be the sole survivor or they are just great hiders.
I also have a Condi, 2 Serpent stars, Coral Banded Shrimp and perhaps others that might snack on them.
That's a great idea (though my hermits will launch themselves to them first I bet). I have a camel shrimp that I tossed in my fuge many months ago (reading that he would eat display stuff). I thought was long gone and pretty much forgot about him. I saw him just the other night when I was feeding the fuge (I know - not necessary, but it's just so cool to see all the stuff like pods and worms that come out of the rocks when you drop a algae pellet in)
brittle star will eat anything it chatches especially the green ones. I lost a few firefish to one.
Now serpent is a different story. I just happen to have one for sale shamless plug.
I have pep shrimp, brittle star and a condy all living peacefully together for almost a year. I dont think it's going to be a problem. The pep shrimp are very fast movers this helps to protect them. They will come out for pellet food.