My two cents to this ^ guy's two cents:
I've never ridden a road clipless system, so I don't know what I'm talking about BUT I have a mountain shoe that has a full carbon sole (Sidi Dominator 6) so I don't understand how it would be any different and less nice than a road shoe. The only difference is the cleat and the tread pattern when compared to the Sidi Genius. Maybe someone can enlighten me on that one. And second, I don't know what kind of mountain clipless you've been riding, but I've never had a foot "ejected" occasionally and I ride brakeless and rely 98% on backpedaling for slowing/stopping (I will occasionally backpedal hard enough to skid during oh-**** moments, but I buy expensive tires and don't like replacing them). I ride ATAC XS pedals with the spring tension all the way up and the cleats swapped (R cleat on L shoe & L cleat on R shoe). The only time my foot ever came out unexpectedly was when I was goofing off and doing a hockey skid and twisted my foot out. That was once in 2 years. I have broken more straps in the same time frame, so clipless is definitely the safer option in my experience.