I purchased a pair last year and absolutely love them. I wear a size 12 shoe and ordered a size 13. The Bog boots are a hair more snug that the Mucks that were on my Exstreams, but not enough to be an issue. I probably don't need to wear as thick of a liner sock under my Merino wool socks....The bottom line is my feet don't get cold, which was always a huge issue for me before the Exstream & G3 bootfoot.
I do a lot of snow/ice covered uneven terrain walking, scaling hills, steep embankments and tricky wading and have never been concerned about the support they offer. The waders a G3 tough, have plenty of storage and are plenty warm with appropriate breathable layers on the legs and waist area.
The Bottom line is I would buy the waders again having used them for a winter season.