Hi, i've had my 245m for about 2 months now and thought I'd let you know my thoughts on battery life. I've kept a daily log for my own curiosity.
I should say I didn't buy it for smart notifications.
I find it really good.
Mine drains on average just 2% overnight and 10% during day. I get this by turning off in the watch settings WiFi and Bluetooth. I've changed backlight for both activity and non activity to off except for After Sunset. I only turn Bluetooth on when I sync. Hope this helps.