From what I've just seen it's built into the dock that comes with the x50 series so it has to be docked in that to work.
But if that's the case then yes it's free
I use one of the TMC receivers on my 720 and it's good, it's not updated constantly so it will sometimes report problems that have dispersed but overall it's been a lifesaver a few times now!
Not sure what these new ones will perform like but mine finds it a struggle to lock onto a signal in a built up area with lots of buildings and houses - as soon as you're on a bypass or something it locks on pretty quickly
I've got the Navcore 9 loaded onto mine and it's good, paired with the IQ Routes technology it's useful stuff, and quite a few times has auto routed me around traffic problems.