The G5 is a very nice bit of kit that will do things that thirty years back you would have has to spend $20k to do but as with all these things the devil is in the detail.
To get the most out of the system there is likely to be a few add-on’s needed in the way of adaptors to get things like the full air data computer functions.
As far as I know there is no ADF input but it will give an HSI with auto-slew and RMI functionality for both VHF NAV & GPS.
I am sure that Garmin have not finished yet with the function software and I would expect to see further improvements to the G5.
The best bit of advice I could give is to sit down with an expert and find out what you really want from the system as the cost of doing the avionic fit right the first time is far lower than having to go behind the panel for a second or third time.