Looks like a washer and a compression spring are all it would take to replicate the Graves piece. Place the washer below the bottom-most nut, I think there's a fat part above the threaded rod (brake adjuster) that you could seat the other end of the spring in, then it's just a matter of getting the spring strength right. If I spend more than 5 bucks replicating this I'll be upset with myself. (I do see this as being very important, especially because I'll wear many different shoes when riding, the touch/feel of the rear brake is never the same, smoothing it out/making it more progressive would be nice)