Transponders have a major limitation in that they are only a one way informer: Additional and separate equipment is required to read those transmissions from other aircraft. The main purpose of a transponder is to inform ATC. FLARM and the like inform all participants with two way/multi way information by transmitting and receiving at a low cost through its own unique systems but of late also through ADS-B therefore it can be read by all: ATC, fast jets, gliders and microlites including powered parachutes. This seems to me the best way to go particularly for vfr only aircraft who are the most likely to be in the mix.
Last edited by Fl1ingfrog; 4th Dec 2019 at 15:24.