My suggestion, check out everything before you commit to anything. Ask other people about a service. There are plenty of bloggers who have been around awhile and they can give you some insight. Chances are, if the deal is there today and it is legit, it will be there tomorrow. It doesn't hurt to check them out before you commit. Remember, this is your book you are talking about. Guard it and take care of it.
I have to look up some links, but tomorrow, I will tell you what happened to me and how I almost lost my book online. Until then, Happy Trails To yo