I have the 5, 6 and 7 Black. The stabilization on the 7 is pretty good, way better than the 6, but that comes at the sacrifice of power draw, which renders the 7 utterly useless in cold weather. I have yet to try the new 8/9 batteries to see is they fix this, but the new blue-tabbed batteries are supposed to be able to support higher power draws to allow for increased processing of the 8/9, so that might help in cold weather for the 7 (15ºF and below). The 5 and 6 do much better in cold weather.
Regardless, you will still need to bring extra batteries.
The 8 Black does not have a replaceable lens protector, so that should completely remove it from consideration. I'm always replacing those front glass pieces. Between my dog being careless when he's on filming duties, and getting bashed up against rocks when I've got one of the cameras, those replaceable front lenses get scratched up with regularity on these cameras.