The main reason I moved to the new Series 4 was to get the ECG feature. I already get a ton of fast heart rate alerts, so it would be great to not only know if it's faster than normal, but irregular. The first time I tried the ECG, it said "Inconclusive", so I tried it again... and again, then waited an hour or so and at least a dozen times later I started wondering if it has something to do with the way the signal is supposed to travel vs the path when wearing a metal band, so I took it off and viola "Sinus Rhythm". I'm not sure if this is a coincidence, but I've never had a good reading with the stainless steel Milanese Loop, and just about every reading with the fabric Nike Sport Loop has worked. I've also modified how I place my finger so that it only touches the button and not my wrist (closing the connection). Anybody else have this problem?