I recently threw a pair of PC, BMX platform pedals on my commuter for fun. The platforms are a little less efficient than the SPD clipless pedals are, but they are also much lighter. Back in the day, I rode steel bear-traps with straps and clips; I never had any real problems with those either. The SPDs work very well too.

I'm going to stick with the platforms for a while since they seem to be a little easier on my knees. I like being able to freely reposition my feet.

As for safer, I fell a few times back when I first started using clips/straps, but then I got used to them and never crashed again because of them. The same goes for the SPDs. After a few hours of riding on the clipless, engaging and disengaging became reflexive. Each style of pedal has advantages and disadvantages. If I were riding 30 miles + on paths without traffic stops, I would want the efficiency of the clipless pedals or clips/straps. For my 15 mile commute in traffic, I'm liking the platforms right now.