Although I rarely rode for most of my adult life, when I did, I always used clips & straps. My wife bought me some SPD pedals & shoes for Christmas and I love them. For me, they are much more comfortable than toe clips (these are very casual shoes with a stiff but walkable sole) and Shimano M520 pedals).
As I then had an extra pair of pedals w/ toe clips attached, I put them on my wife's bike (she fought it but I told her I would remove them after 1 ride if she didn't like them). She loved them. That first ride, her average speed increased by 2 mph and she said she felt she was exerting less effort. Not scientific but they seem to make a difference.