I should have known to wait but I pre-purchased the Sense. Performance was sub-par from day one but now, at less than two months, it died altogether. I bought the protection plan but even with that I'm still responsible for the cost of shipping (!!!??) to return it to Fitbit.
Suffice it to say that you shouldn't buy the Sense and, in fact, I am done with Fitbit altogether despite years of product use.
Apple Watch here I come.