I got a couple sets for fat-biking, thinking they may be a little warmer, but the issues with exiting in snow caused quite a few slow-speed falls for me. It's similar to the CB problem, that the release is based more on angular deflection than spring tension (even though there are springs). Sometimes you get "stuck" in odd slow speed situations trying to release by twisting your heel inwards instead of outwards or just a real odd angle and you can't "pull" like you can with Shimano, so I'll be selling mine. They aren't bad, just not for me.
As far as snow and mud-clearing, yeah the old old shimanos, like 737s, were terrible. The newer style has huge open areas where mud can pass through, much better. The problem in warm-snow temps though is the snow sticks to the cold heat-sink cleat and it will make it hard to clip in. This isn't a problem for me below about 28 degrees F, but in that warmer realm, it can be with new/loose snow. I was hiking the other day with my mini-crampons in some snow and it was doing the same thing, turning my boots into 6" platform shoes, because the snow was "sticking" to the metal. Times work a little better in this situation, but it's not huge IME.