I'm switching to disc brakes before winter, but pretty much all my reasons wouldn't apply to you.
1-the rim brakes aren't so good in freezing rain and other icy conditions
2-during the mud season, the sand and crap that gets on the rims and brake pads really chews up the rims, and the chewed-up rims in turn chew up pads the rest of the year, so I go through pads fast, and my front rim is starting to worry me; I don't want a split rim at speed.