Anybody have experience with either of these, or another
recommendation ?

Steger Mukluks. See www.mukluks.com. Not cheap, but comfortable,
warm, not bulky, nicely hand made. Tested in Mt Washington wave to
-20 F OAT. Vent system on my 20 leaks cold air onto feet no matter
what, so pretty tough test (on todo list to fix before wave camp next
year!). My feet did *finally* get cold. But it took several hours.
Can fly all day at anything above about +5 F with one pair wool
socks. If you want warmer, buy em a size large and bulk up on socks.
Much nicer in the cockpit than any rigid soled shoe or boot.

-Evan Ludeman / T8