True. Don't forget that the Garmin at your quoted price needs to add the connector kit ($$), the backup battery ($$$) and the GAD 13 kit ($$$$) for the same functionality. Those are included with the AV-30, which doesn't rely on a GPS signal for an attitude solution. One of the reasons the G5 certified versions cost more than the G5 Experimental versions is that the Experimental version is bare bones and the certified version includes the connector kit and backup battery. Add those up and there isn't a whole lot of difference between G5 experimental and G5 cerified; both of which are way more than the AV-30. And the G5 should have an external GPS antenna for actual IMC (required for STC'd model). That's more $$. AV 20/30 don't depend on GPS reception like the G5. That's nice to know when the DOD is jamming GPS as is often the case near military test ranges the AV units will still work. Keep in mind the GAD 13 OAT interface is still extra for both Garmin versions. In fact I think Garmin developed the the GAD 13 with OAT probe kit as a direct result of the Aerovonics AV-30 having OAT interface and data included (winds, TAS, density altitude etc). The Garmin also doesn't have built in AOA or G meter like the AV 20 and 30. Remember that the founder of Aerovonics has been involved in most of the the innovative certified glass avionics developed in the past 25 years by the likes of Bendix, Eclipse Avionics, Aspen, UPS-AT and others so this wasn't his first rodeo.
Competition is a good thing. And the devil is in the details with respect to what's included or not included in a base price.
I fly a G5 in my RV3. And an AV30 in my RV8. A Sandia Quattro in my Husky. I installed a dual G5 STC'd set up in a Piper Comanche for a friend. I installed and fly an AV-20 in a friend's Super Cub I have a GRT Mini I have experimented with in both certified and experimental aircraft. Some of these models I would not trust in IMC. Others I would. I have not seen nor heard of a Kanardia Horis until your post (sounds like the name of a Guru on the mountain). Bottom line I really, really like the Aerovonics (now uAvionix) AV series, especially coupled to an OAT probe. I would be comfortable with either Aerovonics units as an emergency backup in the soup.
I don't work or represent any of the manufacturers. YMMV.
Jim
