I've never used supergaiters myself, but the argument that I've heard aginst them is that because they leave the sole of the boot exposed they don't provide as much insulation as you might think because of conductive heatloss through the sole of the boot, especially when wearing crampons, which being metal, are great at sucking the heat out of your feet.
It's funny, I almost never have problems with cold feet, and usually I just go with a pair of leather mountaineering boots, thick socks, and gaiters. Once, in New Hampshire, Using this footwear combination,I was trekking around on Mt. Washington and it was unseasonably warm and raining, and so my boots ended up soaked. That night the temp dropped into the single digits and my boots froze solid. Putting them on that morning was really unpleasant, but after walking around for an hour or so, they thawed out, and my feet actually felt really warm.
And seriously, everyone who has ever worn crampons (and I don't care if you are Mark Twight or Steve house) has slashed their gaiters once in a while, not that it's a good thing, but it's definitly a universal one.