My Flarm seems picks up every C or S transponder in the are that is being interrogated. That's a critical qualifier where I fly because there is absolutely no ATC radar coverage anywhere near our field so the transponders stay silent unless a TCAS equipped aircraft is passing overhead. Even though that doesn't happen the majority of the time I still find the PCAS function of the Flarm quite valuable.

I just had my first ADS-B equipped traffic a few weekends ago when a club member flew through the area in a borrowed turbine powered bird. The ADS-B equipped craft showed up with the same precise location that the Flarm equipped gliders and tow planes do. Nice. (prior to this the only ADS-B traffic I ever saw were airliners passing by miles high and miles away)