asic and overclock:
starting with the asic score. this does represent efficiency and it also sets what the max boost clocks that card will run at out of the factory (this is why a bios flash can help as it changes the asic to boost clock variable). but efficiency has nothing to do with a max overclock of a gpu. a high asic will achieve a more reliable overclocking potential since it is already closer to the overclock naturally. simply put if you have a ASIC 82.9% then you have a Boost 1442.8 MHz, so getting to 1500 is not really all that much meanwhile a ASIC of 65.0% gives a Boost of 1379.5 MHz so getting to 1500 is a pretty significant increase. In the end you are probably going to have to keep those temps significantly lower on that 65 asic card to get a good overclock but this does not correlate to the actual highest overclock that you can achieve.
when overclocking I noticed in your video you said that you never broke 80C. why are you that close to the thermal limit. people use ln2 to lower temps so I would assume you would use all of the cooling potential you have while testing an overclock. do you run all of your tests at 100% fan speed, if not you really should when wanting to know what your max overclock is. you can then lower your fan speed to see what the max temp that overclock will run at but I have noticed a temp barrier of around 60C while overclocking and I keep a slightly aggressive fan profile to keep my boost clocks but I have to stay under 60C to keep it completely stable.
so the above is really all just to say that everybody should absolutely upgrade to the new ssc+ or the ftw+. the new cooler, the new voltage control and increased limit, the extra 2 phases of voltage, the mosfet plate, a second bios switch (if you wanted to flash now you can safely); these all increase the longevity and reliability of the cards and are all things more than worth the upgrade from the old sc at the max potential cost being 50-100hz. you would have to have such an exceptional example of the gtx970 to not upgrade for what is a significantly better overall GPU.
in the end I would bet that 90+% of the gtx970's will get to 1500 on the core with the correct temps and maybe a bios fix if needed. In the overclockers world sometimes you have to be willing to do a bios flash to get the most out of your card or increase your fan speeds but these are the joys of overclocking not the why has this not been done for me attitude.
coil whine:
as far as coil whine I get none except for when I am f@h and doing a core 15. I will get a noticeable but faint whine from the gpu. I run this rig pretty nonstop and it seems that the coil whine is getting less and less with time.
frame pacing:
http://www.pcper.com/reviews/Graphics-Cards/Frame-Rating-GTX-970-Memory-Issues-Tested-SLI read through these 4 articles for a great understanding of the situation and some good testing. these reviews are still missing some info on shadow of mordor and what happens with frame pacing and runt frames at that 3.5 barrier but those are referenced and covered by others.
AMD CF:
your experience may have been bad but I started running CF with a 7870 tahiti le (replaced an evga gtx560) and a MSI twin frzr 7950. I later swapped out the 7870 for another MSI 7950. I never ran into issues at 1440p @110hz. frame pacing was an issue that came into play at first and for a long while but I ran a fps cap of 60 fps and at first I only had a 1080p monitor so it always seemed to run well for me since I was not pushing a resolution or performance limits. later I bought a 1440p and by then frame pacing was inline with nvidia and as of now sites like hard ocp say that amd is better at frame pacing now than nvidia. these things change with every driver but to say AMD has not caught up is wrong. I understand that AMD has a resent history of driver issues but nvidias past is not exactly great either so who ever is performing right now is all that I care about.