Nothing beats heated socks. Period. And connecting thru heated pants, is more convenient than extension wire. But all in all nothing else even comes close to the performance. You wear them over a thin pair of non cotton socks to avoid getting hotspots from the wires. Thin liner or dress socks will work fine. Just avoid cotton.
My only issue, [but I've accepted] is that if there is a failure in your heated gear. [it has happened] and your in a position that will matter, you need to carry a backup pair of heavy wool socks.
I tried heated insoles. They did not work nearly as well as the socks. I wouldn't reccommend them.
I've also used Dryguy Bootgloves for 3 years and they do help, but if you get the fabric strap wet and walk on it, it will wear thru very fast. If you have a stitching awl and means to keep, [and don't mind] repairing the strap then it would be cost effective. If you think this will be a problem, then you might spend to much $ replacing them as needed. Eventually the shifter wears thru any way. They extend the comfort zone enough to notice, but not a large margin.
I just bought a pair of each of these Neos Overboots to try over my Garne Oiled Balance boots. A pair of insulated, and a pair on uninsulated. I have not had the chance to try them out yet though. My concern is that they might be bulky enough to make shifting a problem. [especially the insulated version] And I'm not sure how long it'll take for the shifter to wear the instep. If they don't work out, I'll keep them for non riding use I guess.
I'll post up how these work out.
Like I said earlier, nothing is like heated gear.