TBH I am not particularly bothered by noise of my computer, as long as it is reasonably quiet on idle. I really only care about gaming performance because I want this PC to last for at least 2-3 years minimum. Going my back to the noise thing I am going to have the PC in my bedroom, and I usually keep it on a night because I don't like having to turn my PC on at 3am when I can't sleep and I want to play on my computer (not very often but it does happen time to time), hence my previuos hesitance to rid of my SSD which the only reason I dumped that idea was when I saw that PC with the 970 and the i5-4690K and most of the time I will have my headphones on anyway (Sennheiser HD 201s if you were wondering, not the greatest but they have lasted me 2 and a bit years so I can't complain for £30).
I think that 90% is pretty much the real world. Just look at this: http://www.computerbase.de/2014-10/nvidia-geforce-gtx-970-test-roundup-vergleich/4/ They tested a lot of 970 and 980. Some have more noise than others, but basically all of them have it. The problem is that most people won't be able to differentiate the noise from the rest of the system so they think they don't have it. Yet that problem exists since they released the GTX 680 (i had one, as i now have a noisy GTX 780). But AMDs aren't free of that problem either.
Well i must be part of the 10% or so, since my has MSI 970 has no coil whine, at least that ive ever noticed.