The Garmin GV is excellent, no glare screen is vey good take out and hold in direct sun light , and can see it clearly. Certified version is about 1000 more than non certified version. Legal and paperwork sure will be nice if you have an issue.
It is now legal as one of several (only as one!) such as Attitude or as DG, (possibly others not sure as did not need that) as noted above, sure will help out in a tight spot if you get IMC. Altimeter is excellent and dead on altitudes up to 20k, (just did several IFR Certs and had it checked with regular altimeters. The Pito static guy said it was impressively accurate if set up. Airspeed and Alt have a "anticipator" marker that indicates rate, increase or decrease just like in a glass cockpit Just small. as mentioned no vacuum needed with it, I suggest you look up and see what Garmin has to say about what it can do. It is very light, and has very shallow depth in instrument panel, (I think about 2 inches with out back up battery, and about 4 with battery. Should easily give you ability to mount where many instruments hit the bracing behind panel. I keep my "antique gages" such as airspeed and altimeter for legality, but the Garmin is way more accurate.
Draw backs- if tying into ILS or GPS for course guidance it is very small indicator.
I am such a fan after trying one in my C 180, I put two in my new Bonanza panel. and one in the Mooney, and one in the Cuper Cub. rebuilding the Glassair now and will install one as needed in its new panel. I should become a dealer!! ha! They are very good.
