Great boot (but not the lightest)
I just bought the Mamooks after trying several pair of various B3 boots for Scottish winter, summer alpine capable of being fit with fully rigid crampons.
Close runners in the end were the new Boreal Cerro Torre (replacing the Ice Master). These were a full 70 grams lighter per boot than the Mamooks. I had them both at home for about a week, and found that both were excellent.
What made me decide in favour of the Mamooks in the end were the way that you could really adjust the fit of the boot using their 3 zone lacing system - loosen up the front for the walk in, tighten them up for either front-pointing up a waterfall or for the long descent down steep, hard pack neve.
And even though they are heavier than the Boreal Cerro Torre, they are still more than a hundred grams lighter than my B2 boots...