Naturally, memory clock wouldn't affect the hashes produced. This is not the memories job to provide calculations. The only thing you benefit from by lowering mem clocks is significant heat reduction produced by your gpu. Also, you may get more stale shares if you're in a pool as your gpu is taking that much longer to process and it tends to miss the last bit or so of a calculation. This is what generally causes a stale/invalid share (false information due to gpu leaving out a bit or two of info).
In my experience, lower mem clock to about 300 Mhz for a relatively stable experience. Doesn't cause too many invalid shares and may reduce your temp by about 8 degrees Celsius depending on your card.
Good sir, I do say you're quite skilled in the art of Talking Out Your Ass.
Reading your paragraph reminds me of when a woman goes to a mechanic, "he said my muffler bearings were going out, blinker fluid was low, and I somehow made it to the shop with only one transmission and need the second one put back in asap!"