trex3 is rugged, balance has speaker (but speakers are problematic with sports in water), body measure and (but I'm not sure) skin temperature measure. All other is the same.
You have really nice watch face with the mountain, what's the name? Can you show the nice watch face with AOD (always on display? Also, can you use touch screen in system menu or need to use physical button? How's the button/touch screen in water or cold weather?