First, I want to thank you for the ZRF! Btw, L. Lynn Smith also made
another ZRF of Abstract Chess :) I'm happy to see that many of you like
this idea.
About the 7+ stacks, I didn't think of them as valid stacks, but I
didn't say anything against either. Indeed there are tactical
considerations, because it means queens able to give extra powers to
adjacent friends with losing their abilities. However, it seems that the
cost and tempo is too great. I believe it's best to keep 6 as the max.