The Target location is owned by the City of Sandy Springs and they've been toying around with it for some time on making it the city's center. The hold up are the adjacent businesses on the southeast corner of the property. There's a dry cleaner, Waffle House and a couple of others who aren't looking to sell or move and are in somewhat of a battle with the city on a possible imminent domain situation. Until that is settled, I wouldn't expect any movement of an outfit like CHATTCOM to invest in a move that would be for an uncertain amount of time.
Not sure about the Brookhaven situation but it sounds plausible. Their other options would be to use one of the other city or county centers and since many of them have ongoing problems, the new city of Brookhaven wouldn't want to start off with any potential of getting a black eye if they're looking to make improvements for residents. Using one of those troubled centers could lead to a lack of confidence in the city leadership to make sound decisions upon it's creation.
The North Fulton cities have explored the Atlanta UASI system but have yet to make a decision on what they'll end up with. They're likely shopping around for cost comparisons of building their own DTRS versus being a tenant on an existing one. The bean counters are going to want those types of costs comparisons versus advantages/disadvantages to help make a decision of what they should or shouldn't do.
Maybe someone on here has the inside knowledge to fill in more details of the facts.
The issue mot people have with then UASI overlay is just that: it's an overlay and doesn't have the needed in building portable coverage or the channel capacity to accommodate multiple agencies dispatching and tactical talk groups without sacrificing its availability to roaming users. That and the IMO OUTRAGEOUS per radio access fee assessed for interoperable users.
Poor planning and administration leaves it idling most of the time, reminds me of the last statewide TRS project of the 1990s, it was a great idea on paper, but in practice it sucked. Not enough coverage, high user fees, and no firm buildout plans. We see how well that worked out didn't we?
Hopefully the right questions will be asked, and we will see a good RFP like the one Floyd county did to procure their 700/800MHz DTRS. This is the kind of planning, research and work that SHOULD be done, and allow for all players a chance at the field so we get the best value for our money, and performance guarantee and not just write a blank check to a vendor and let them run the show.