Definitely get one and try it. Personally, I think it's very easy to use while wearing gloves.
Its size is a factor here. The Millie's blade is about the same length as that of a Benchmade 710, while the handle is significantly longer and wider (keep in mind that's width [top to bottom], not thickness). It's a great outdoors knife, and I imagine it would be excellent for mountaineering; it's lightweight (lightest heavy-duty folder I have), very strong, has a nice, long blade, has a large, comfortable handle, and has a very strong lock.
Some say that the liner lock is easily disengaged... I say that these people haven't actually used one very much (if at all). The locking liner on my Millie is WAY stiffer than any other lner lock knife I've ever used (including my Emerson). The large cutout is therefore perfectly OK, since the liner is so stiff; it's never come loose by accident in any of my experience. And, the large cutout makes it easy to unlock the knife purposefully with gloves on, where a smaller cutout would make it difficult.
The way the handle is shaped sllows for a very safe, secure grip. I've never slipped and cut my knife hand with the Millie, while I certainly have with some other knives.
In short, I think that it may be a perfect choice for your intended uses. Go ahead and get one, try it out, and tell us what you think. If it turns out that you're not a fan, then you can easily sell it for close to what you paid (it's a very popular knife).