I have a 10L Katadyn bag i use quite a bit. I absolutely love it and every time I take it out I wonder why the heck I pump water with an MSR or squeeze a baggie of water.
This past weekend we hiked up to a FS cabin on a lake and stayed Fri-Sun. Two people, two dogs, lots of tea and coffee and "water foods". Could have got by with the first bag full, but after finding a bit of open water closer to the cabin filled it up again for good measure.
Water filters in Alaska generally take a beating. It flows fast but I keep filters clean and work hard to find the least silty water; even if that means building a micro sed pond.
I don't take it on alpine hunts (no where to hang it usually) but I've never not been anything but pleased.
Fun fact: If you fill it up in the cold and have to walk too far to a warm stove, the drip (?) tube will ice up and takes a bit to thaw out.
That said, if you need to filter water for REAL winter camping, this probably isn't your filter. But all filters struggle to hold up/function in freezing temps...
Edit: Just saw your losing comments on freezing... I don't know of any water filter that can freeze and maintain it's original filtration capability.