I use SPD, I would love to get ahold of some of those prototype xtr pedals in the links above. I have saw one pair in the wild on a Van Der Poel bike that someone bought.
I have used Candy's but the cleats wear too fast for me. 1 set of SPD cleats lasts all year no problem.
Heard nothing but good things about the ATAC and have wanted to try them but I have SPD through multiple bikes and don't want to go thru the hassle.