I train CF every day. Have loved using the watch for the past 5 days. Zero problems with tracking heart rate, and I've found it to be accurate.
To the above people who say it is always "searching," are you choosing "other" from the activity app and then sliding to have the bpm always viewable on the watch face? Mine has been working perfectly, and ranges from 90 bpm in my warm-up to 181 during sprints and WOD.
I do bootcamp and have used my 42 SG twice with excellent results also. I was very impressed with how well it tracks and displays my HR. I've also got mine set to have the BPM visible and all it takes is a quick look at the watch to see where my HR is. Awesome tool.