Weighing in!
I just bought the Merells, below, with Vibram sole, mainly for icy conditions on my walks. They are warm enough for me to at least -10C with Smartwool socks -- but do keep in mind that I am mostly in motion in my footwear, so my feet do not get anywhere near as cold as if I were still.
I also have the tall Uggs, which are very warm, but not very good on ice (although they are fine in snow) and, as you report, they are quite cumbersome.
Another pair I own which are a good hiking blend -- Garmont. These ones are really good for very cold conditions (rated -20C, I believe) and they seemed to fit me better than Saloman (which just don't fit me), but -- alas -- they didn't fit as well as I thought because after a season they created a sort of painful bump on my heel; I have given up wearing them as a result, even though they were terrific for just the conditions you describe. It was a fit, not a quality issue, though. So you might try this brand as they were lightweight for hiking. Something to note -- the soles are quite rigid, which is good for some activities but not others.
My old snow boots were Kamik. They were great for warmth (rated -40!) and weight (they weigh almost nothing!) but they were not good on ice and they fit small so I ended up bumping my toe in my smaller size and swimming in the larger size, which is why I did not replace with the same type but tried a new brand.
I have tried Santana. It's a really solid Canadian brand. I had their boots as a kid. The fit on the styles I have recently tried did not work for me, but the quality appeared to be excellent and in general they get good reviews. I think it is value for money.