Coors, I guess it depends on how much walking you'll be doing. The 600 will make your feet sweat more if you're walking all day. I would suggest getting the 400's and take several pairs of extra socks. Keep an extra pair or two in your day pack. When your feet feel especially hot and sweaty, cop a squat, take your boots off and air your tootsies for a minute. Take a couple of baby wipes and wipe your feet down. Then, after your feet have dried, put on a fresh pair of socks. Put your sweaty pair in a baggy to cut down on your scent. A fresh pair of socks will make your feet feel practically brand new after a day of walking all over the mountain.
Make sure you take some wool socks (and extras), just in case you run into snow.