The DMR format is a cheap way to go narrowband, and TDMA digital compared to P25 formats. MotoTRBO is the DMR offering from Motorola. There are several other vendors for DMR radio systems, but because Motorola is the biggest name in the game, they do get the majority of contracts. They are also the only vendor that has an DMR TRS currently.
The reasons so many agencies are going conventional DMR (TRBO or otherwise) are: Cost - DMR is a lot cheaper to implement than APCO P25. TDMA Digital - Currently there is no APCO P25 Phase II standard for conventional, so to get the advantages of 2 Slot TDMA digital, your only choice is DMR currently. So by going with DMR, you now have narrowband, digital, and TDMA which allows far more efficient usage of the bandwidth for an reasonable price range.
Boone SO is indeed DMR, not sure if they run Encryption on it or not, so can't advise if you can hear em using DSD Plus and get info using DMR Decode or not.
Abandoning AWIN is not smart in my opinion though. Not using it full time I can understand, but to completely fly off it and lose the Statewide interop is just not smart. I have posted multiple rants on the whole issue of cry about no interop, then abandon the interop solutions you cried for in other locations, and won't get that started in this thread so we can keep on topic.