Little late to the conversation, but I'm in the same boat. I fly Airbus's to pay for my real passion. I own a 172M that I purchased from a doting owner about 4 years ago. I initially "upgraded" the original avionics to an old-school package consisting of a pair of KX-155's (one w/glide slope), a new Garmin Audio panel, a new SigmaTek A/I and D/G, and I threw away the NDB. I also replaced the starter, vacuum pump, and ignition harness, and installed fine-wire spark plugs. Finally, I replaced the voltage regulator. Just last week, I started the new phase of avionics upgrades to my incredibly trusty and solid aircraft. I installed a G5 attitude indicator along with a SkyBeacon ADSB-out Nav light/strobe. I also installed a carb temp gauge that I got off a guy doing an upgrade in the hangar (HUUUUGE bang for the buck investment)! You would be amazed and alarmed at how many times you are flying around in potential carb icing conditions. Next, I plan on completing the upgrade with a GPS and a second G5 to act as a HSI/DG. Engine monitor next. I haven't decided on the GPS yet (650? 750?) but suggestions are welcome. Autopilot is last; my plane flies straight as an arrow hands off. The point of all this is, I too looked at faster aircraft, but I just can't justify selling an aircraft that I know to be sound in order to get an unknown aircraft with slightly better performance. My 172M has taken me from Maine to Florida and back with ZERO problems. An extra couple hours over 500 miles will never cause me to give her up.