FLARM -
On the question of common system ADS-B works with PowerFlarm and Pilot aware.
If you want either of them to work well you really need to install external antennas the internal ones are really not good enough so if you have PowerFlarm and its not working its the installation you would need to look at not the device or software.
I fully agree the co-ordination is not good but in the end its going to be ADS-B. This is favoured by NATS and the CAA. If you get PowerFlarm or Pilot Aware and ADS-B out we will all be working together as this is what is common to both. Both also work with Skydemon.