We have tests of FLIR/DVTel/ioimage analytics here. And Bosch IVA here.
Both of them now include a calibration process where you measure objects and distances to give the camera better perspective information, and it's helped accuracy in the Bosch IVA. Neither were particularly prone to false alarms in our tests.
The ioimage analytics now have an auto calibration process, as well, though we have not tested it. When we do more analytics testing we may take a look.
Bosch says IVA performance is better in the newer cameras like the 5MP starlight, as well, and I'm told they may be adding some learning features in upcoming releases.
One major difference is integration: Bosch has a lead here. Their analytics integrate out of the box with Genetec, Milestone, and Exacq, that I know of. DVTel's, at least at the time of our test, were not integrated with any platform but their own.