My input to those rules- at least for featherweights- dont agree with them. 20% of 12kg is 2.4kg. There are a LOT of feather spinners whose discs weigh more that 2.4kg! 500rpm- very very slow by featherweight standards.
24- OK not so much an issue with feathers, but it strikes me that one size limit applied to all the weight classes contradicts the claim that this rule is made with all weight classes in mind.

This needs further discussion on this thread for featherweight builders- most decent feather spinners will exceed 2 of those limits. It is too much hassle and red tape to have most good feather spinners subject to review, whatever that may entail.

Just some thoughts.