Thanks. I've been using Vivosmart 3 for a couple of years now and am generally happy with the performance. I am thinking similar to you - everyday usage for a week(s), non-invasive, but accurate enough to detect emotional stress.

I am willing to make sacrifices on accuracy but it would be great to know the extent of the sacrifices. E.g. Vivosmart 3 calculates HRV, but I have no idea about the algorithm behind the calculations and how well it would match HRV calculated e.g. and from ECG signal.