Streaming music for several hours over LTE (without phone) will use more battery. Add in the other things mentioned, and the battery will take a hit.Interesting comment regarding battery life (4 1/2 hours). I don't use mine for running, never for phone call, yes for heart rate and streaming for a few hours a day (from internal storage, I have a LTE watch but no plan) and I get approx 3 days battery life.
Surprised the running makes such a difference.. does it enhance the metrics gathering? or is it simply the calls? (Suspect so...).
Am not however wedded to the idea of 'watch only' for my services (yet). Watch alone for email/messaging etc. is ineffective and probably reflects my true MVP.
Edited to add: I am streaming over LTE right now.