FWIW, I went ahead and got the Garmin GTU 10 to use for now. Works great so far, it's accurate to ~15ft while sitting on my workbench in the den.
I was under the impression that the AT&T network used would be shuttered in about a year from now, however I found this on the site when setting everything up:
"The connected services provider for your GTU 10, AT&T Wireless, has determined to cease operations of its 2G network by approximately Jan. 1, 2017. Unfortunately, due to the AT&T Wireless network circumstances, the third-party services necessary to support the network connectivity operations of your GTU 10 unit will be impacted. As AT&T Wireless disclosed they plan to fully discontinue service on the 2G wireless networks by approximately Jan. 1, 2017. At this time, there is no viable alternative of such services; therefore, after such date your GTU10 unit will no longer be operational. We apologize for the inconvenience."
I was under the impression that the AT&T network used would be shuttered in about a year from now, however I found this on the site when setting everything up:
"The connected services provider for your GTU 10, AT&T Wireless, has determined to cease operations of its 2G network by approximately Jan. 1, 2017. Unfortunately, due to the AT&T Wireless network circumstances, the third-party services necessary to support the network connectivity operations of your GTU 10 unit will be impacted. As AT&T Wireless disclosed they plan to fully discontinue service on the 2G wireless networks by approximately Jan. 1, 2017. At this time, there is no viable alternative of such services; therefore, after such date your GTU10 unit will no longer be operational. We apologize for the inconvenience."