Have the new Forerunner 55. One thing is that it has the version 3 heart rate monitor. The Venu 2 has the new version 4 heart rate monitor. I also have the Fenix 5 with the version 3 heart rate monitor and it worked OK most of the time.
For some reason the version 3 heart rate monitor works really well on the Forerunner 55. So for any one out there on the fence about the 55 because of the heart rate monitor, Don't worry it works great. I did see one review where the guy thought it might be the fact that the 55 is so light that it doesn't "bounce or wiggle" on the wrist so it gets a better reading.
Anyway just thought I would let you know that the same heart rate monitor version 3 works great on this watch.
Ken