Unless your bare feet get cold in the summer, I wouldn't consider insulated boots until you're spending most of your time in 20s and under temps.
Here in Vermont, the cold-susceptible ice fishers and late-season stand hunters wear 1200-gram insulation boots. Those are usually rubber. I bought my first pair of insulated boots at 400 grams last season, but that was just because there was a Danner sale I couldn't pass up. Darn Tough socks have kept my feet toasty for the past decade... including -17 days on Mt. Mansfield.