So I have a series 3 42mm and have had it for going on 3ish years? Love the watch but it’s not getting updates anymore and I’m stuck on 8.8 so looking to upgrade. I can either buy series 9 new for full price, or a local acquaintance has a series 7 44mm new in box for $175. From my understanding, the main differences are the temperature sensor and better processor for the 9. Is the big price increase worth it for the 9?