A bunch of questions:

Do you find that timing chains last longer than drive chains? Does it make sense to rotate the timing rings each time you replace the chain in order to spead the wear?

With regards to the Park CC-2 Chain Checker: It seems that all recommendations for chain replacement use 1/16" elongation per foot of chain as the criteria, yet the CC-2 tool measures stretch as a percentage of chain length; Why is that? I just got one and measured both of my tandem chains at .5% wear with about 550 miles on them. This seems a bit excessive, but do chains have an initial stretch or "break-in" and then stretch slowly after that? (The new chain on my single is so tight that the chain checker wouldn't fit even at the 0% setting.)