PLayed with Timmy Oneblonde's unit in Morocco and it was pretty impressive.
If you are out with mates and don't mind being a little bit illegal, the Rino is also a bloody good unit that will give you buddy tracking (so you can go directly to them or see their location, as well as send them radio texts) as well as automotive GPS stuff with routing and OS/Topo map capability.
We used those for several years in Morocco too, one as lead bike unit, a second as tail end charlie unit and a third in the support truck.....works very well
They are legal to own and use in the UK, but the radio frequencies aren't......in all the years I've had one though, I've not heard any more than a squeak from mine- they are supposed to use the same frequencies as they do on ships for deck to deck comms, but even living here next to the biggest commercial sea port in the country, I hear nothing.