I didn’t get a full quote for G3X as I decided to go ahead with Dynon already. However, the equipment cost for dual G3X + GFC500 was noticeably more than dual screen Dynon. Even single screen setup was more expensive, even though I had G5 AI already.
What’s funny, I couldn’t even get quotes from any avionics shops in the area. They never called me back or replied to my emails. What is attractive (and contributed to my decision a lot) in Dynon installs is that any A&P is authorized to install it, and they sell directly to consumer (me).
I was lucky that my shop got a good avionics guy already, so we could schedule the setup quickly and go ahead.
In terms of installation efforts, Dynon wiring is much simpler (Ethernet in custom pin out and DB9 connectors) and it comes with most of the harnesses already pre-wired. That shaves a lot of time from the installation costs.
It also comes with the avionics shelf that hosts the screen and most of the components (ADAHRS, ARINC, EMS and backup battery).
Speaking of components - they are smaller than Garmin counterparts, so easier to mount.
There are also install kits/brackets for servos, specific to the airframe, so that saves on install time too.
Oh, and even the data subscription is free for nav data and $99/year for georeferenced approach plates, airport diagrams and VFR sectionals/IFR charts.
This is the supplied avionics shelf/screen mount with ADAHRS/EMS/ARINC in the stack, backup battery (for one screen, both screens and backup EFIS have their own batteries) and ADS-B receiver on the side.