Another vote for MTB shoes on a road bike. I hate walking in road shoes, and if you're riding a hundred miles or more, it's nice to walk around once in a while. Another thing is road crossings. If you have road shoes, you'd better hit the cleat right the first time, or you get racked when your foot slides off. Painful, plus there you are in the middle of the road fumbling around. MTB shoes, OTOH, stick to the pedal no matter if you're clipped in or not, so you can clip in when you are out of harm's way.

That said, my Sidi Lightnings (road) are feather-light, soft, comfy, with nice stiff soles.

Nanci