I switched to clipless specifically SPD M520s last year. Even though my route is a mixed paved and unpaved surfaces I find that it gives me better foot integration with the pedals.
I had clip cage type pedals on my hybridized mtb and I always find it annoying to put my foot back in. I got fed-up with them and purchased a pair of m505 w/ detachable platforms. This allows me to ride with regular shoes on days when i don't need SPDs.
Great thing is, my cleats SH51 works with both pedals. I use a mtb type SPD shoes. So no awkward clickety-clack when walking around.