You'd be surprised at how little extra momentum (speed or weight) you have to add before disc brakes become essential. For me, the aha moment came when I starte

You'd be surprised at how little extra momentum (speed or weight) you have to add before disc brakes become essential. For me, the aha moment came when I started pulling a 40 lbs bike trailer - then you really don't want soft brakes when approaching a junction with cars. I installed some Avid Juicy's on 180 mm rotors and they're awesome - even now when the bike trailer is 70 lbs.