I have not seen any noticeable increase on returns from memory OC, and it tends to cause stability issues. better to just run stock memory IMO.
While every GPU is different - for Raven some OC settings do produce more. There are some on discord that are uping the voltage and reaching max OC levels with some stronger returns.
But, for the most part, JackIT's work speaks for itself. Hiss work is on 1080TIs and I have seen similar results on 1070TIs and 1070s.
https://bt.irlbtc.com/view/3385643.0;topicseenEnemy 1.08 @ 100% TDP [ no OC Vs. +250 mem ]
April 24th, 2018 - Full Test Results.
#1 * | Enemy +250 mem | 337.39 RVN
#2 -0.90% | Enemy no OC | 334.40 RVN
Enemy 1.08 - mem OC & power settings test
April 21st, 2018 - Full Test Results.
#1 * | (100% TDP +250 mem) | 150.92 RVN
#2 -5.90% | (80% TDP No overclock) | 142.51 RVN
#3 -6.01% | (80% TDP +250 mem) | 142.37 RVN
But you are correct that it's not worth pushing it if it causes any instability and/or crashes and resets.