I'm on my second pair of Shimano's, currently SD66's. I don't remember what their predecessors were. I find them comfortable to walk in and the soles stiff enough to pedal in with full pedal cage SPD's. My toes especially love the open toe. The SD5's don't seem that different, but you can't tell much from a picture. But damn, they've gotten expensive - the next pair will probably be sourced from EBay. They're still not cheap but at least closer to reasonable.