I'm using 8x MSAA along with 8x Sparse Grid SuperSampling 

 

Specs - I5-4460, 980ti, 8gb ram

The only person who can answer this is... well, you.

It depends on so many other variables, including your personal preference.

I'm not sure what we're supposed to say really?

If you fly into heavy clouds youre going to get your FPS hammered. I have the Asus 980ti STRIX and I can only go 2XSGSS or else I'll get 20 FPS in OVC clouds. I'm running at 1440p if that helps. 

Same here, 980Ti from PALIT running 1440p and everything above 2xSGSS is an overkill. While higher SGSS modes might still work when lurking around using an A2A plane in a remote ORBX region, it is definitely not if I am sitting in the AS A320 VC on a busy airport with overcast conditions.

Higher levels of SGSS work fine as long as there aren't a lot of clouds or alpha textures like trees (OrbX Darrington, for example). Personally I stick with 2X as well. There's a slight amount of shimmering compared to 4x/8x, but performance is much more consistent and it looks fine. Running a GTX 970 and 1080p.

When you guys use 2xSGSS do you also use 2x in p3d, i do see the trees shimmering a lot without using NI

I still wonder why so many people keep asking questions like "will setting X work".  Some people will always respond with "you will get your FPS hammered", some people will anser "no problem". It depends on so many other things, like all your other settings.

 

So I wonder - instead of asking, why not simply try for yourself?

Trying different settings and starting a few flights to see if it looks good and if your FPS gets hammered in heavy clouds (for example) will probably take less time than it takes to ask on a forum if heavy clouds will get your FPS hammered. And the answer will be more accurate.

 

I still think that the only person who can answer the original question of "is it overkill?" is the creator of this very thread.

@tolip2 - You're right of course, but the question/thread has still made the linkage between high SGSS settings, cloud cover and what may have been an otherwise inexplicable drop in the OP's FPS crystal clear. So no harm, no foul and I think the thread has proved it's worth.