In all honesty i think about 80% of the forum run a grind. You dont "need" on, but it will improve your braking by probably about 5x You could also invest in some BT yellow pads, which are sposed to be really good on a smooth rim. But in the english weather, if you get caught in the rain, you wll probably find that the smooth rim slips on the back wheel where it wont on a grind. But you dad is right, grinding the rim is detrimental to the life of the rim, even if it is only slight. But its less detrimental to your health to have confidence in you brake when jumping on a rail.