As the owner of several "smartwatch" with a transflective display (Pebble, Pebble Steel, Pebble Time Steel and Amazfit Bip), it does make a huge difference in battery life and I wouldn't downgrade to a smartwatch with a battery life of under a week.
As far as I can tell the Amazfit Blip is the latest with a transflective display. If there was an option to install a different OS on it, I would love to use one.