I have the 125 and it does what i need it to do but you asked:
1) the amber led background light is hard to read at night where the 135 has a white one which might be better.
2)depth on the 125 is 900ft. and the 135 is 1000 ft.
(like you’d really use that extra advantage)
So the outputs different and the backlight is different. Hard decision to make for the extra money
Good luck