I've been looking only at the advertisements for direct mount brakes.

Looking at them it appears a bit strange to me. The cables appear to come in at a 90 degree angle to the frame and while I can see the cable guide, I can't see where the inner cable is affixed. I suppose that it is obvious if you have a set in your hands but it isn't at all obvious in the pictures of them I've seen.

I will go with the idea that since they are connected on both sides instead of through a center bolt that they are stiffer and have a more "direct" feel it seems a little ridiculous that you have to have a frame specifically built to take the new kind of brakes. Though the same can be said of disk brakes.

I rode in the rain yesterday and while I was being careful I was taken somewhat aback by the amount of time it took the wheel to go around a full revolution to clean the rims of water so that the rim brakes would work. This was worrying enough that I continued to put them on time after time to keep the rims clear of water as much as possible. But all it took was not putting the brakes on for a quarter of a mile and "Look Ma, no brakes". These were carbon rims with special carbon brake pads. I don't remember this much trouble with aluminum rims but then what do I remember?

Since it requires the same amount of time for a wheel to make one revolution and clean a disk off just like a rim brake I'm wondering why they make the claim that disk brakes work better in the rain. If you jump on the brakes in the rain the disks allow you to somewhat break the water layer with sheer force. But as soon at the disk makes a full revolution doesn't it greatly increase the braking force? The only time this occurred to me was going down a hill and hitting a bump which jerked the disk brakes on and locking the wheel up and throwing me off the bike in a very uncomfortable manner.