My present winter setup combines a thick wool sock and the Weezle sock with a Rockboot one size oversize and it's real warm for at least an hour in the mid-30's, but I want to improve the duration.
Since a Rockboot one size oversize is barely big enough for my current insulation, I'm going to try 2 sizes oversize and increase the loft a little and use Smartwool (Merino wool) with the Weezle.
Dave C
Please forgive the self-quote.... it's just to give context for this update....
I had wonderfully warm feet the entire dive of 74 minutes in 39-degree F water yesterday. Not even a hint of any coldness! Max depth was 60 ffw.
I had replaced my old thick wool sock with two pairs of Merino wool socks for the same overall thickness. Wore my usual Weezle socks over that.
I also replaced my 1-size oversize DUI Rockboots with a pair 2-sizes oversize.
I used to have a little constriction when I wore 1-size oversize, but yesterday everthing fit nicely in the bigger Rockboots. Not tight, not sloppy. Laced loosely as usual.
I still need to get a bigger fin pocket and that might even help a little more.
By the way, "Merino wool" socks vary greatly in their content of Merino wool. These were Fox River Mills A2097 Trailhead Trekking Socks with 77% Merino wool, 22% stretch nylon, 1% Spandex. This was the highest Merino wool content I found.
They're pretty pricey locally ($16/pr), but a buddy and I went in on an eBay sale of 6 pairs of "Not Quite Perfect" for a total cost of $39.50 delivered. Imperfections were insignificant.
For me, using a higher grade wool sock and getting rid of contriction improved the warmth of my feet.
Sure, "clown feet", some might say, but I'd say warm clown feet!
Dave C