I just bought a VS 4 to replace my VS 3, and I'm very disappointed because some useful functions for me have been removed:
1) stress in the last hour, it was nice to just tap and see stress evolution in last hour,
2) HR in the last hour too,
3) When running, VS3 displays lap speed rate at end of each lap,
3) test of VO2Max just with a tap.
SPO2 sounds an unuseful gadget and Body Battery doesn't tell more than stress level and I don't like to have to wear watch each night.
The big benefit I see is outside readability of screen by a sunny day. Another benefit is the relaxing timer which is better to follow.
Am I wrong ?