The H-Tac does seem to be 1mm taller, going by the front sight that is recommended. I ended up going with the Tac. With the 5.5mm front sight CZC recommends, my pistol shoots slightly high (1" at 25 feet, about 3"-4" at 25 yards). The 6mm would actually have beem perfect. YMMV.
The CGW sight also appears to be quite a bit taller, they recommend a 5.6mm front sight, but that's measured from the top of the slide. CZC measures from the bottom of the dovetail base, which adds ~2mm.