Some FRSKY transmitters can be fitted with a module to allow them to be used with different systems. I modified my Taranis X9e by adding a Spektrum module. For a modest outlay for a second hand Spektrum transmitter, and a few hours work with a soldering iron, my Taranis works with FRSKY and Spektrum receivers. The Taranis X9D Plus takes plug-in modules for JR and Futaba, much cheaper to use these than swapping out all your receivers.