In reply to TobyA:
You're spot on Toby, that's Alligin from Beinn Dearg.
5 out of 5 for winter mountaineering is probably fair but as you say that will depend on your definition of mountaineering. Note they don't get rated at all for summer alpine climbing (a bit unfairly?), mixed or ice falls, all of which are categories for the Mont Blanc Pro on the Scarpa website.
I did some short lived front pointing on moderate angled snow on BD, and there is enough flex in my size 47 that you know about it, though it seems fine for grade I sort of angles. I'd guess the brief nippy bits of the BD traverse rate about II but that's rocky scrambling ground which means you're never on front points for long. On the strength of how they feel on me I doubt I'd pick them over a B3 for a sustained grade II like an icy gully. No chance I'd do anything as steep as your average IV in them. But that's not to say I won't at some stage find myself getting the rope out while wearing them, they are definitely on that borderline.
Small-foots I've climbed with over the years have sometimes seemed to get by with boots that I'd find too flexible, and anecdotally that's not unusual. So doubtless some folk would be happy in Mantas on stuff that I wouldn't be. In any boot there's a lot of added leverage from the extra length in the upper sizes, and the sole construction will be the same whatever size. If you have big feet then you'll probably also be heavier (I can speak personally here) which may also come into it.