Well, a few hundred grams of extra weight is definitely not a big thing for me.

The thing is, I just want to know that if one brake fails during a long descent, or a steep one, or both, that there is a second brake to cover for it.
I'll likely just use the regular rim brake 99% of the time, but when something happens, I believe it would feel pretty good to have...

Are disc brakes difficult to add yourself? I assume I'll need a new front wheel...