If I'm going to ride for speed, performance and basically a workout, i'll use my clipless shimano pedals and shoes.
I'll use regular pedals with toe clips if I'm riding for transportation (getting there without being sweaty or tired) or if I don't feel like putting on my super suit and going down my pilot's checklist.

I am getting into riding more with regular shoes and toe clips. I will soon get a stiff comfortable shoe that will allow me to ride to a town and then walk around without problem.

For touring, I you will sacrifice performance, but the benefit is great if you intend to walk around a great deal or hiking a bit. I'm not going to lie, I KNOW that clipless pedals makes the riding easier. i've done the same route with regular pedals and clipless, and i was more tired without them.

BUT - it feels dam good to be able to get off your bike and walk around comfortably, not feeling like a duck.