I have a v4s and i did the software update couple of weeks agos and have been monitoring it. I. Workout 4-5 days 30-50mins, and week run some days 1:30h with gps only 2 - 3 times too.
The brightness is set on 20%, vibration high, only email notification, calls and amazon (not sponsored), no gestures, always connected to my phone, no spo2 reading just when i want to.
I have right now a defaukt watchface but because of preference wanted a minimalistic look but i have 2 watch faces installed (the fr645 and 55 one), menstrual cycling widget, sun and moon widget, weekcalendar widget, no music because i run with my phone.
And i can say that it has been holding on 4 days easy, yesterday I charged it with 28 %
The 6.50 have been ok not perfect kinda afraid if i install something it would drain my battery then, but so far thats my "review" hope it helps *i didn't bought my garmin new its second handed from a friend *