I have not noticed a change based on my somewhat casual scanner listening while I'm in my shack. Fire has been quite busy as usual, with traffic accidents and medical calls. All I could guess is that a move to 700 MHz might well be the result of all of the live feeds and resulting over-reaction or rumors on social media and in the newspaper. IMO the live feeds have a growing negative effect because of the number of listeners who don't understand what is being said or is actually happening. Folks who make the investment in a scanner typically have a better understanding of what they are listening to since they are more invested in the activity. And the feeds also make it cheap and easy for the bad guys to monitor while they do bad guy things, obviously. That alone makes me shake my head and wonder...
I am not blasting those who do feeds, sorry if that sounded that way. I'm simply speculating at what's happening in Granbury (if anything), as you are also inquiring about, since we both live here. I have used feeds now and then and they are quite useful especially listening to an incident outside one's local coverage, where friends or family live for example. But they are (again IMO) definitely a "double edged sword".
I will pay a little closer attention to HCSO traffic to see if it sounds like they are obviously handling some things on other frequencies or modes, now that you have piqued my curiosity. And they do use Spillman a fair bit, as you may have also inferred from the voice traffic, for any information such as close patrol, you know, more personal stuff. Since they know everyone is listening they do it on the laptop. At least they are considerate of Hood County residents', by not broadcasting that you (your address) are on vacation and they are making a close patrol to check your house!
Jerry