Dave Butler wrote:
I asked my avionics guy about this or something similar and he wrinkled up his
nose and said those were for homebuilders.

Of course. They're a modern technology concept (all the way up to the
1980's), rather than the usual hodgepodge that passes for an avionics
system in most production planes.

I didn't get any more detail about why it was a Bad Thing.

Because avionics shops make their money on installations, as well as
taking a markup on avionics - not on repairs. Since any A&P can
install avionics, and since anyone can get a big discount buying the
avionics online, if these hubs ever became the nom lots of avionics
shops would fold.

Michael