Weight wise? I have no Idea but I don't think they are that much different.

I'M on my 3rd bike with them, 1st is a recumbent high racer I still have and 2nd was a 29er that got stolen. When looking for a replacement for the 29er one of the requirements was disk brakes. The day I got the new 29er I ended up having to do an emergency stop. I hit the brake and the rear wheel came off the ground. The girl that ran the stop sign had eyes as big as dinner plates. Hopefully next time she will use her neck as a swivel and not a phone holder. I have never had a rear wheel come off the ground while riding using rim brakes. I'm a clyde and have been since the age of 13.

I don't think I would get a bike with/out disk brakes ever again.

Then again I'm sure there are people who swear at them just as much as I swear by them.