Unless things have changed in the last couple of years, Tubbs and Atlas have very different binding systems and I'm not talking about how they attach to your boots. Tubbs uses a pivot rod (not sure what the real term is anymore) while Atlas uses a flexible attachment. The difference; tails on Tubbs will drag in the snow while Atlas tend to flip up as you walk. While Atlas shoes WILL flip snow up on your back, I personally prefer this attachment system to the free heel tubbs shoes. For me, it makes breaking trail up steep trails much easier. You can drive the front of the shoe into the snow with a much simpler kick than you can with the tubbs shoes. For this reason, you should try both shoes to see which works best for you. As far as MSRs, they just don't provide the float someone of my aah, stature needs. I use 8x30s and if I have a big pack, I think I could go bigger in fresh powder. 99% of my snowshoe experience has been in the Catskills on trails that were rarely hiked in winter so if you are planning on using snowshoes on packed trails you might be able to get away with smaller shoes. That is definitely something to consider when buying shoes.