I went for the full Dynon avionic suite. The Dynon intercom unit combines all the sound outputs from the Dynon HDX, the remote radio, and other sound sources and output them to the pilot and copilot. Without the INTERCOM unit, I am not sure how the pilot and copilot can hear the radio with the Dynon radio setup. The Dynon HDX warnings including the bootup voice are also fed through the INTERCOM. There are also allowance for two COM sources. I only have one radio so the 2nd COM source isn't wired. There is a copilot PTT lockout if the pilot PTT is active. There is one input jack for other external device (music?). I am sure there are other features I miss but this is my first time attempt at wiring, and connecting anything this complicated.
Other note regarding the physical unit: the intercom unit extends about 4 inches back from the panel, and the wiring loom extends another inch past the connectors so you need to plan carefully. The most complicated about wiring this is to plan out all the soldering of the ground connections and to make sure they aren't cramped inside the small connector housing. I made two attempts at the wiring before getting it to talk correctly.