Roy Garden, in his original post says Flarm is useless.

I don't know how his and his friends systems are set up, but mine works GREAT.
I usually get a 7-10+ mile range on mine and that is a long way. Some of my friends are reporting longer ranges with higher performing antenna's

The Lead and follow flight is very difficult to do, as it is so easy to get separated. Then the endless Where are You radio calls start, not much fun.

At the Logan Ut. XC camp back in I think 2016, I hooked up with Tim Taylor; him in his Ventus 2 and me in my LS3a. Tim flies fast and I soon lost sight of him. Through Flarm I was able to "see" him and fly his track and meet up with him at the turn around point up by Alpine Wyoming. he waited for me there and then we ran back home, but once again I lost sight of him but could see him the whole way on the Flarm. That was a great day for me. And I would not have made that flight on that day without Tim in front of me.
These novice level lead and follow flights are tough to do, I think the lead pilot needs to be in a lower performance glider, and the following pilot HAS to stick with the leader, or It quickly falls apart.