Well I played around with RCR more tonight and you can do it but I don’t think it is beneficial unless you have perfect gear. My gear is quite good and I have to give up offense to get rid of CotA.
I was doing my testing with my speed run set where I run 105’s in the low 6 minutes (average). In this setup I run with the CotA, Ruthless, Enchantress, Gogok. CDR is 68.24%, RCR is 33.8%. I changed the gem in my helm to Topaz; used WC charge, templar, Earthen Might, CDR is 62.63% and RCR is 42%. Anything less than these changes and I am can get starved of fury. But with this setup I am no longer Fury starved.
Look at the damage I had to give up to remove CotA. Ruthless ~12%, no enchantress so one less break point ~2.5% and CDR change ~9%. What did I get for giving up over 20% of my damage? Some defense, no Ancients cluttering the screen and more cool-down management making sure I don’t become fury starved.
Doesn’t seem like a good trade off to me.