I have MTB SPD pedals on my road bike. I wear Keen bike sandals year-round all rides. The sandals have a stiff forefoot plate but flex enough to be comfortable off the bike.
I've worn them on bike touring trips (50 miles/day), RAGBRAI (450 mile week), coffee/breakfast/social rides, commuting to work (17 miles ea way), fast 100k rides, some steep hills where I struggle getting the pedals to keep moving.
The sandals can be loosened up to accommodate thick wool socks and a toecover inside the sandal. They dry quickly. The rubber toe bumper keeps toes warm in winter. The open sides keep feet cool in summer.
They have very good traction but would advise not wearing them at work all day unless you're just sitting at a desk.
They seem to be 10,000 mile shoes - the forefoot sole plate eventually cracks. Still usable a while after that until the insole tears as well.
I have the commuter III's still new in box but haven't tried them. Fit seems different.

YMMV, they aren't for everyone.