Deciding between 255 & 955

Female, small wrist… but would like the Hill and Endurance scores as I like trail/mountain running. I prefer the lightest watch possible. Are these metrics actually useful or a bit of a gimmick? I definitely want training load as have used that before to train. I haven’t look at more expensive watches simply because they are heavier. The 955 looks gigantic though! Or should I be waiting to see about the 270/970 to future-proof the watch?