I narrowed it down to three models:
Itronics ITB-250HD : no GPS, only capable to capture 720p, other than that seems pretty solid, size 97mmx40mm
BlackVue DR500GW-HD : 1080p+GPS, inconsistent feedback regarding video output, size 118.5mmx36mm
Cowon AW1 : 1080p+external GPS (optional), new camera...