I rode Look from about 1989 until two years ago. I changed to SPD-SLs. I wanted something that was mostly the same, but I was tired of ARC cleats always squeaking, wearing out or breaking. The yellow rubber tips on the SPD-SLs work exactly as advertised, better grip on the road and a set of cleats will go a whole season of 6K-7K miles. Keos would have been my other option, but I was just kind of burned out on Look at the time.
Same. I recently switched from Looks to SPD-SL’s. I was also tired of the squeek, and wanted a similar pedal. My final straw was when I realized I was popping out of the Look’s on rough roads. The SPD’s are much cooler looking (not so bulky), and definitely snap in. No problems whatsoever with squeek or unintentional release. And dirt cheap (around $30 with cleats at Pro Bike Kit)
I recently went back to Looks since I got a new Look 586 tri bike. I was using Time RXS which are my favorite. I like the Looks. They are fine- not quite as elegant as the Times in my opinion (no recentering force) but they work just fine. No problems.
Another thing to consider is foot stability as your cleats wear.
With the Look system the surface that wears from walking and putting your foot down at a stop light is the same surface that supports your body weight when riding. Most Look cleats wear unevenly and create an angled support surface, similar to running shoe wear. This can lead to instability for your foot.
I have found that most of my achilles issues occur when my cleats are worn (I have been a Look Pedal user for a long time). When I replace the cleats the achilles issues tend to subside.
With Shimano SPD-SL, Time or Speedplay the surface that supports your weight when you ride does not contact the ground when you are unclipped. This means that you will always have a flat interface between your cleat and pedal as your cleats wear.
I have loved my Look pedals but I will probably be making the switch this year to something different as well. Right now I am leaning toward a season on SPD-SLs.