Write spec for Harmony Mining · Issue #3672 · zcash/zcash · GitHub was a particularly controversial one. (It never actually got to the point of writing a ZIP, but was discussed on GitHub which is the relevant point here.) Make sure to expand the hidden-by-default comments and read all of it!
From the relatively little I’ve read of it, it seems great. But it doesn’t seem to be doing anything that Zcash doesn’t have other venues for (mainly GitHub and the R&D Discord); in fact there are a whole bunch of Zcash GitHub tickets that look just like ethereum-magicians.org threads in terms of style and substance. Note that my interest in Ethereum is heavily skewed toward the cryptography, protocol design, and other technical issues, though, so that will be biasing which threads I read.
You’d have to ask Ethereum folks that.