Xfinity Home Key Fob

i have an Xfinity Home Security install scheduled and we are used to having key fobs, but the feeling that I'm getting from both Xfinity technical support and from other posts is that they may no longer be supported or at the very least they are trying to discourage me from getting them. My sister has some that she is no longer using (SMC) and wanted to see 1) if anyone else is using them and 2) is the compatability of the key fob dependant on what base you have?