Buddy who just showed up from the HTs to the squadron told me they got the 650.... couldn't believe it. So.... a training plane for basically all aircraft that do not nor will they ever have IFR GPS capability, that is equipped to fly LPV approaches, yet the Herc, which would benefit greatly from this product, is stuck with 20 year old stuff that is just shoved together and works some of the time? Nice.
While I'm not 100% certain, I'm under the impression that what they found was that one of the cheapest ways to upgrade the TH-57 fleet to be ADS-B compliant was to install a GTN-650. I've seen a few GA guys take a similar route with similar Garmin products (usually the 650 or the 900 I believe). It just so happens that we also now have LPV and VNAV with it as well. I don't think the going in mindset was "let's buy an upgraded GPS!!!" as opposed to "what's the most cost effective way that we can upgrade a 30+ year old aircraft fleet to be in compliance with FAA directives?"