In reply to Benbrady11:
Flex in the ankle is fine, in fact it's easier to walk with a flexible ankle - if you've ever walked in skiboots you'll know what I mean. There's a trade off when it comes to winter/ice climbing. stiff=heavy (usually) but the stiffer b3 boots tend to have much more insulation in them.
There are some B3 boots that bridge the gap between the B2/3 range such as the Trango Extremes (incidentally the ones I own) which aren't as stiff all round as the Nepals, say but offer better insulation than the Manta but will take any crampon.