Like others have said, depends on where you are.
I have used a 9-10" boot for several years, but went with a 6" hiker last year and really liked the extra movement my ankle was able to get without being secured by all that leather higher up like the 10" boot has. I found I was able to hike longer without my legs or feet being as tired, but when it came to sidehilling, I twisted my ankle 3 times pretty bad.
One time I thought I had really done some damage that could have hurt my hunt but it turned out okay.
I think for me, hiking from a truck camp or something like that in regular Colorado terrain a light hiker may be okay but I prefer a little stiffer boot with better ankle support to prevent any problems from arising.