I have always used the SPD system and find it works well. I know that the proper road clip-in pedals have slightly better power transfer and may reduce hot-spots on your feet.

That being said, I have never had significant soreness or hot spots from SPD. SPD shoes are easier to walk-in as well.

My advise is consider SPD. Decide whether you would still like to ride the bike with conventional shoes sometimes. If so, consider a pedal with SPD one side and cage on the other.

As far as technique goes. You can play with the tension and also a useful habit is to unclip on at least one side when riding in traffic or in terrain where you may need to get a foot down quickly.

Also, when climbing you need to remember you have very little reaction time so if you need to stop, give one or two powerful strokes to give a small time buffer to get at least one foot out before you lose momentum and stop.