You might not need that much insulation unless you are planning to be sitting all the time or know you'll be in really extreme cold. I have 400 gram boots and hunted in -20 temps, 2 socks and never got close to cold. I second SaskHunter, the more you can try on, the better, but it's hard to tell until you really get them out on uneven ground and put some hard miles on them before the problem areas start to show. Granted there will be some break in time, but they should feel really good when you put them on the first time. I'm currently using Schnee's for a lighter everyday boot, and Kenetrek mountain extreme 400 for a heavy boot. I got the Kenetreks used for under $200 since I had heard some love them and some hate them and didn't want to risk ~$500 testing them out. I am very happy with both boots. If you're not turned off buying used boots, it's a great way to try out different brands without all the cost, as you can usually get most or all your money back on high quality brands.