This is the poorest design for comfort and support I have ever seen in a wading boot. There is virtually no cushion in the upper collar of the boot and this will make your fishing experience on the river very miserable when you are on the river for hours at a time. For a boot that cost around $150.00 a pair, Simms has done a poor job on this boot's design, they basically put out a "Lemon" on this one. Simms usually has a good reputation for the product they puts out, but they obviously miss their mark on this one. I would not recommend this boot.
I just returned from 7 days of fishing in Yakutat. I wore the boots all day long every day. I walked several miles in and out many days. The boots flex forward nicely but offer good lateral support. The Vibram soles are amazing. I found no flaw and would recommend them highly.
My foot size is 11w. I ordered size 11 and immediately returned them for size 12 -- nice fit with neoprene footies. My son tried my boots. He also is size 11. He's ordering a pair (size 12).
I'm just a guy with no allegiance or loyalty to any product. This boot is a winner. Only question remaining is long term durability, but there's no way to assess that now.