So after 21 hours of mining at a slightly lower settings I have some data to report. after 39 hours under the setting above in the article I was getting 1.856 shares/min (63 Mh/s)....and after 21 hours at reduced settings I'm getting 1.870 shares/min (62.5 Mh/s)...which is better! The epoch is higher now as well (which increases difficulty, albeit slightly). So you may be on to something! I reduced the core clock to 1300 and memory clock to 2250 for each card.