I've had two pairs of these pedals on my bike, and love the big platform and float. I've never had any knee issues with these. My complaint with them is the squeak that lots of people report, and the fact that after about two years the right pedal broke (both pairs). Could it be a string of bad luck? Maybe. Having just broken the second pair, I'm currently debating whether I should get another pair, or get out of a bad relationship.
I was a long time user of Speedplay and they were second nature for me. I'm a fan of TIME bicycles and components so when Speedplay was purchased/merged (and I didn't like what I saw from Wahoo) I decided to give these a shot. I pretty quickly adapted to the engagement and disengagement process and I really like the large platform. I do feel that I am able to transfer more power when compared to a Speedplay type pedal. However, after only a couple of hundred miles the squeak developed and it is extremely frustrating. I want to love these pedals and I want to convert all of my bicycles to them, but I just can't do that yet until I find a long term solution to that squeak. Or until TIME fixes it.
I switched from Look to Time about 8 years ago. I am really happy with them. The pedals have a large comfortable platform. The float is a knee-saver. Only drawback is that the cleats wear down quickly, but they are inexpensive to replace.
I have been using Time pedals for over 20 years and these are among the best ones that they have produced to date. They work flawlessly and I have never had any knee problems using them. Highly recommended.
The Time iClic feature is nice and allows for easy re-engagement of the cleat. However, the pedal-cleat interface squeaks when riding (as described in this review httpsroad.cccontentreview252571-time-xpro-10-pedals) and the small plastic faring, as Time calls it, broke within the first week or two of use.