i did post the photo and it did catch my eye and i did ask some questions but don't know that much about it. i don't think the spring is the main attraction (tho it does look a bit odd) - Col you may be right about its function.
the brake plate looked fairly machined - i don't know if it was made new or modified from standard. the guy who made it says one shoe is reversed (they are offset so he started with 2 sets) and its got an internal linkage and custom cams. i don't know how it adjusts other than by disassembly and fiddling. he said he'd just done such adjusting and had improved the brake efficiency a lot - way better than a sls.
i think its great people are finding new variations on solving these old problems. if we are going to be frozen in time we don't have to be frozen in ideas.