The 1080 is well documented to get around 30% gains over the 980Ti which isn't "minimal". I've done several benchmarks to see the improvement. I've also benchmarked at 4K to see a noticeable difference. I guess it boils down to the software as there's quite a disparity depending on what game you're playing. I don't think DOOM is the best example to be honest as the game looks great at 1080p due to how id make their textures. Take the Witcher 3 though, I could just about get a steady 27-30 fps all settings maxed @ 4K with the 980ti now I can have an average of 40-45 which is a much smoother playing experience. Still not quite 60 fps but will do me fine.
I also sold my GTX 980Ti to upgrade to the 1080 so the cost wasn't as bad. I think many people can at least get some returns on their old cards when upgrading.
One last thing. You're talking about improvements of graphics when upgrading. Well, developers are already taking advantage of that if you play games like The Division where everything maxed out is a hardware killer. You've also got to consider the visual improvements running games at 1440p or 2160p with everything maxed which makes a massive difference in how games can look. The 1080 simply handles those resolutions much better. So there is a visual upgrade compared to playing with a 970 at those resolutions which to be fair isn't going to be playable or you're having to dial back the settings to medium - low (see video)
https://youtu.be/BcgUvx6a7RQ
In my video I averaged 38 fps using The Division benchmark tool with the Ultra preset@ 4K (which isn't even the max settings for the game). In the above video the 970 Turbo is hitting average 22 fps (not really playable) at medium/high settings. Imagine it chugging at Ultra settings.
https://www.youtube.com/watch?v=O8jxWVuIKnc
Just ran a benchmark using my basic Founders Edition Overclock which gives a 7-10% gain over the stock settings and got an average FPS of 45.8 Ultra Preset 4K. So do the maths, that's double the FPS of the 970 and with extra effects. If I dial back the settings to be an exact match with the video. I get average 56.5 fps.
I also sold my GTX 980Ti to upgrade to the 1080 so the cost wasn't as bad. I think many people can at least get some returns on their old cards when upgrading.
One last thing. You're talking about improvements of graphics when upgrading. Well, developers are already taking advantage of that if you play games like The Division where everything maxed out is a hardware killer. You've also got to consider the visual improvements running games at 1440p or 2160p with everything maxed which makes a massive difference in how games can look. The 1080 simply handles those resolutions much better. So there is a visual upgrade compared to playing with a 970 at those resolutions which to be fair isn't going to be playable or you're having to dial back the settings to medium - low (see video)
https://youtu.be/BcgUvx6a7RQ
In my video I averaged 38 fps using The Division benchmark tool with the Ultra preset@ 4K (which isn't even the max settings for the game). In the above video the 970 Turbo is hitting average 22 fps (not really playable) at medium/high settings. Imagine it chugging at Ultra settings.
https://www.youtube.com/watch?v=O8jxWVuIKnc
Just ran a benchmark using my basic Founders Edition Overclock which gives a 7-10% gain over the stock settings and got an average FPS of 45.8 Ultra Preset 4K. So do the maths, that's double the FPS of the 970 and with extra effects. If I dial back the settings to be an exact match with the video. I get average 56.5 fps.
