I commute in SPDs, so definitely spend more time in them. My issue is that I can feel the pressure from the cleats through the sole, since the cleats don’t bolt into the stiff carbon soles, but rather into the metal backing plate which is just separated by a thin piece covering and the insole from my shoe. This might well vary by brand, but definitely when I come back from a morning ride and swap my Specialized road shoes for my [actually slightly stiffer–more carbon] Specialized commuter shoes, that pressure point in the middle of the foot bugs me for a few minutes. So for on the bike, I definitely find the road shoes more comfortable, but for ability to walk from my parking garage to the showers, etc. I’d much rather have spd mtb or touring shoes.