Having got through a fair number of running watches since graduation, I have to say the most hit and miss feature on them has always been the Heart Rate Monitor. Bizarrely the more expensive and high range the watch, the worse the hrm connection has been and the best was my original Garmin 220 which locked on every time and gave rock solid results. I am using a Suunto Ambit 3 at the moment and have more or less given up on its HRM.
However today my cardiologist had me fitted with a full on high tech dedicated one bolted to my chest, whcih will record every beat 24/7. It looks remarkabky like the Fisher Price 'My First Tape recorder' my kids had as babies, and is already driving me crackers, but I am looking forward to seeing the data it produces. Particularly when I do hardcore metcons. Am toying with doing 150 wallballs and burpees tomorrow morning just to see if I can make it burst.
And yes, I do have my dial turned up to 11.