[howdy20012002]

I have lots of hermits in my tanks
Personally I like them
I think that they do an excellent job of cleaning up any excess food or detritus. Plus I think that they are cool to watch.
However, as they grow they need shells. They will kill each other off to get those shells. So if you are going to get them, ensure that you have a few shells lying around in your tank so that it gives them a new home.
As well, they can go after your snails and kill them off as well. In fact, I have heard that zebra hermits are particularly bad at killling off snails.
Although, as far as I know, all hermits are considered reef safe, they have the tendency to knock your corals around as they climb around the rocks.
You basically have to weigh the pros and cons and see what suits you.
If you don't care about losing a few snails or have smaller corals that can get knocked around by a clumsy hermit, then a few hermits, IMO, make a nice addition to any tank
Hope this helps
Neal