I have a pair of 1000's and used them in early fall(archery).The weather was cold and wet so I cannot tell you how they would be in warm weather but you could always wear thinner socks.The amount of insulation value that you want is going to depend on what type of circulation you have in your feet. If your feet get cold easy the 1000's will work fine, if they do not then I think the 400's will be just as good. I think they are the best boot on the market. I used mine last year in Id. for elk (archery-sept.), Wy. for deer(rifle-oct.), Co. for deer (rifle-nov.) and Az. for deer (archery-jan.)and worked fine in every climate. Hope this helps? What ever you deside you will not go wrong with this boot. You will replace all your other boots once you try these!
Bill