Speedplay vs. SPD-SL to me boils down to how much you have to stop on your rides. I prefer the SPD-SL becasue around here, I can ride for an hour+ without having to clip out more than once or twice. When riding in areas with lots of stops, I would lean more towards the Speedplays. I like zero float and like the bigger footprint of the SPD-SL and it just boils down to preference. I would also sat that if you don't have any aches and pains with your current setup then I would not switch.