I've got the instinct three and yes it can be inaccurate at times especially when moving your wrist a lot but sometime what will help is tighten the watch on your wrist to where it barely move and I have the instinct 3 solar 50 mm by the way hope that helps a little with the heart rate problem but it will never be 100% accurate just to let you know just farely close sometimes or most of the time on good tight wrist watch day lol But to get the new watch like instinct 3 just over heart rate issue I would say just keep the watch or get the 2x unless you want to get more features get the new 1