fwiw, I think you get used to any pedal and if you've already used Time, you'd cope with the Shimano or Looks easily cos they 'present' for engagement anyway. The Shimano generally gives you a wider platform which I think has some benefit.

If looking at weight, consider both pedal and cleat cos the Speedplay cleats are so huge, although I think lighter than they were initially. I think they'd be awful to walk in, but ymmv. From memory, Shim/Look q factors are very similar. You could have a look at stack height as well if that's important to you.