The system changes have had some degradation on the signal, but not much. Yes, they have narrowbanded. I think a larger challenge is in finding 12.5khz compliant repeaters that have the wattage out of the old repeaters.
Now, as for a county the size of AC not using NXDN or TRBO:
I have been testing the TriConnex system for my business for the past several days. I've successfully used a portable to talk to my dispatch base from everywhere in AC, as far west as Ohio, as far north as Eerie, as far east as Westmoreland county, and as far south as WV. The dispatch base is in Pittsburgh. It is a Connect Plus TRBO system, and it works every time and is as clear as day.
AC doesn't need full-county coverage though. They have all of their police, fire, and EMS dispatch and operations channels separated into regional zones. As a daily user of the East EMS system, which went on the air as a narrowband UHF system, I can say that within it's service area, it has very few flaws. I can even key it up with a portable in the northwestern corner of the county.
As far as the OpenSky system that was proposed for county government, I can confirm through a discussion with the county radio supervisor that the system has been scrapped. This is the same supervisor who confirmed AC's continued support of conventional UHF, who confirmed that AC will not be joining the ICORRS system, and that any digital county channels going on the air will all be mixed-mode, and will be P25 Phase I.
I can say that after the narrowband switch, my conventional business UHF system for my own ambulance service suffered great losses, and that it has become unusable. That is why I'm demoing TRBO.