For me having the feet attached to the pedals is purely a safety issue. I went and bought toe clips the day after having my feet slip off the pedals at a stoplight with a large pickup behind me in the rain, and that had happened before. Keeping your feet on the pedals is a prime safety issue.

I bought SPD pedals and shoes last fall and rode with them up to now, and they're OK, but I'm switching back to toe clips. I hate having to go inside to put on special shoes when I want to get on my bike and go somewhere, and if I'm ANY more efficient in SPD than toe clips, I sure can't feel it. I do think pulling back on the pedal is a better spin motion than trying to pull up, at least in the 2 years I've had to work with toe clips and the 6 months with SPD. Pulling up still doesn't feel good to me, and if I do it for long it hurts my legs. But I get a fair amount of power out of pulling back, and I can do that for a long time. But I can do that with toe clips too if I just point my toes a touch.

FWIW, I've never had any problem getting clipped out, or getting my shoes out of toe clips. I've never fallen over due to not getting out of the pedals.

My feet have to be attached in some way to be safe, IMHO. But doing it again, there's no way in hell I'd pay a dime for SPD; for me it's pretty much a waste of money. Toe clips for me.