We use Cisco Any Connect that authenticates against AD, but is not tied to any kind of GPS and it works for us just fine. Except for deployment, I see no need in using GPS.
If we use GPS for anything, it's with RADIUS for our wireless network. That works in one location but not the other. And this is only because both locations have different wireless systems and in how each system implements RADIUS and authenticates a laptop against an OU.