Folks, I agree with Anne that we've been having a somewhat circular re-discovery of the pros/cons here. I believe that the best way to address this is to capture all of these points in one doc -- this would be a just a little extra work for the current participants, but super awesome for the future folk.
For example, Domenic started such a doc for another custom elements contentious bit: https://github.com/w3c/webcomponents/blob/gh-pages/proposals/Why-Upgrades.md. Please help break the cycle of re-discovery :) :DG<