So I didn't get another upgrade... Not yet. But, a friend of mine just put a GFC500, a second G5, and a JPI 730 into his already-nice 172, and I just got back from going flying with him to check it out. My experience is mainly with the S-TEC 50 and 60-2, King KAP 140 and KFC 150 and I have a combined 1400-1500 hours behind those. (sorry for the poor picture quality, it was near sunset so lots of glare and shadows) So, as to what's in this plane - You can see the dual G5s, JPI 730, GNS 430W, and GFC 500. It's also ADS-B equipped, with a Lynx NGT-2500 hooked to the 430W and GTX 327. I don't think anything really matters to the GFC 500 except the 430W and G5s, though. First of all, the biggest impression I got was that we're in a different world now. The other autopilots I've used were all analog, and whatever digital gear they were coupled to was still feeding them an analog signal. With the GFC 500, the brains of the autopilot are actually in the G5, so the integration is very tight - Very much the opposite of the KAP 140 in the G1000 DA40, which I felt was exceptionally poorly integrated. Where that shows up is that there's really no "GPSS" as such any more, at least not as a separate mode, even though GPSS is still happening. The G5 knows what the nav source on the 430W is, so if the 430's CDI is set to "GPS" and you hit the "NAV" button on the GFC500, the G5 annunciates "GPS" as the roll mode. If you hit the CDI button to change it to VLOC and there's no signal, the GFC500 will revert to "ROL" mode, again annunciated on the G5. Like any other GPSS, this setup will nail the turns perfectly on a GPS "T" approach or really any GPS flight plan. But, I wanted to give it another challenge to see how it coped, so I set the 430W to OBS mode, dialed in a course to a nearby VOR that was 90+ degrees off our heading, then set it to HDG mode and hit NAV to arm that. Because it was going from a heading to a GPS course, I think it couldn't pre-calculate the turn the way it would on a purely GPS-based plan, and thus it didn't draw the turn on the 430W like it did with the other turns, but it did intercept the course and turned inbound toward the VOR. Because it wasn't a pre-calculated turn, it wasn't quite as smooth - It began the turn by rolling into a full standard-rate turn, then eased it out to about 10 degrees as the course wasn't coming in fast enough, and then rolled a bit more just before completing the turn. But, that's something that none of the autopilots I've ever flown before would even be capable of, at least not without a significant overshoot of the selected course. Quite impressive. It also executed near-180 degree turns in the flight plan flawlessly. Another thing I noticed - No more "arming" things. On my KFC 150, after preselecting an altitude, I have to hit "ARM" or it'll just blow right on past that altitude. On the GFC500, we set it for an IAS hold in the climb, and then just set the altitude bug to the desired altitude. The vertical mode annunciation on the G5 showed "IAS" in green and "ALTS" in white. 200 feet from the selected altitude, it switched to "ALTS" in green to capture, and then "ALT" to hold. No more ARM button to forget! In both roll and pitch axes, the currently active mode is in green, and the next selected mode, if any, is in white. So, a heading to intercept an approach would show "HDG" in green and "APR" in white until intercepting, at which point "APR" would be shown in green. Very easy to read what it's doing, and the buttonology is similar to what I'm used to, yet simpler without the extra buttons. This one was set up without the optional trim servo, and when it needed the trim changed (which only happened once) it just showed "TRIM DOWN" in yellow just below the center of the G5 AI. We didn't play with the envelope protection or LVL mode yet, but so far I'm pretty impressed.