Somewhat annoying, as doing a 'diff' is probably not enough.
It'll also become slightly messy if pg's statement from a month ago becomes true, and there will be new versions of arc coming out in october / november. If we pick up features from different versions of arc, would the changes compared to arc2, as well as the changes compared to arc3 need to be documented.
I guess the value of forcing good documentation of the changes is that it becomes easier for pg to distill a new arc version out of the mutants that the community is spawning, as they'll have their features well documented.
