Hello newton27,
I was using AndrewP's F-Chat module for a while. It was working OK, although some modification and improvements were done for the time we have it on our website. I really can't remember why but later I decided to go with Cometchat. One of the reason I can remember is Cometchat offers mobile apps for Android and iOS while F-Chat doesn't.
Now-days all is about mobile gadgets (phones, tablets) and in my opinion it is good to offer users, members a mobile version of chat system.
Same goes for RMS Chat. I do not own "RMS Free Chat" but what I want to say is that no matter which version is installed on Dolphin, both are Flash based and such does not work on mobile devices....., so users are forced to use it/them just on PC.
Kind regards
Mayki