Carbonfiberboy 

We also have a spare wheel with an Arai mounted. We never use it except for loaded touring in unknown terrain. V-brakes work fine for us riding in the mountains. Big downside for us with rim brakes is that we ride in the rain a lot and need to replace one rim every year due to wear, i.e. rims last 2 years. Yeah, it takes about 50' to wipe the water off the rims. Can seem like an eternity when the FedEx truck in front of you suddenly hits the brakes. But our frame has no disk mounts and we don't really want to go through the frame mod and repaint. In the famous tandem group coast-down on Mt. Ventoux, the rim brake bikes were the only ones not to have issues. There were no Arais (2 lb. penalty). Overconfidence and maybe lack of feedback. I know several rear disk bikes which have warped their disks, one that overheated - the bike went into the woods but was OK. Nothing's perfect except maybe dual disks with big laminated rotors. But there's the weight again, so kinda back to the Arai. Gotta get ride of the heat somehow. But disks are certainly potentially safer. Arais don't do what they do.