I biked for about a year without clipping in. Then I made the switch. Wow! What a difference! I get MUCH more power out of each pedal stroke when I'm clipped in. Instead of wasting energy trying to keep my foot in the right spot on the pedal, the clip does it for me. So all of my motion and energy goes into moving the pedal smoothly and strongly. Now I can't imagine doing a ride of any length without the benefit of being clipped in.

I do 'cheat' a little bit by not having clip-in-only pedals. Mine are platform pedals with a Shimano SPD clip system installed on one side; smooth, flat 'traditional' surface on the other. When I'm coming to halt or worried about something like a dog running out into the road, I'll gently clip out, flip the pedal over and use the flat surface for a few pedal strokes.

I also have my clip-in tension set pretty loose, so that anything stronger than a hiccup releases the cleat almost automatically. So, if I panic and can't turn my heel out in time, I basically pop out straight up! The set-up has been working almost perfectly for me for over a year now.