You are right, my nephew is in the same boat. It isn't that big of an upgrade. What killed the conversation for him was the no sli for down the road. He is planning on saving for the 1070. But if you are planning on single card for its life span think of it like this, you are on average getting about a .17-0.32 fps/£ upgrade (depending on the title) plus everything you mentioned previously. Hopefully that helped you in some way. 😐

I purchased my card for 280€ + shipping costs, so I expect the gap to be of some euros + 16€ of shipping applied byEVGA. No interest in SLI, so it should really a matter of bunch of cents.

Ok some real math now that the 1060 is available to the step-up program (for 279€):
I saw digitalfoundry comparison between (What I guess are) stock 970 and 1060, it seems we are between 10 to 20% of more performance on all games tested (@ 1080p  ).
In my specific case having the SSC version of the 970 and having the possibilies to step up only to the gaming edition (so "stock" frequencies), this should fill even more the gap between the 2 cards (i'm not really aware of what is the % gap of performance between stock and SSC, but assuming that stock VS stock is 10-to-20%, SSC VS Stock I think could be something between 2-to-12% (the SSC version was compared or really near to stock 980 in several gaming scenarios).
 
So, again, power consumption:
120W for 1060
180W for 970 (IIRC)
 
And now the math (personal but can be arranged with your own economics):
 
I got my 970 SSC for 279€ (+ shipping, not included)
The 1060 costs 279€ + 16€ of shipping + other 16€ for returning the 970 (i can lower the return cost but it takes time :D )
 
This means I have to manage 32€ for the upgrade.
 
Assuming that each KWh of power costs about 0,20€ (at least in Italy), my plan is to go on par  by reducing my power consumption. This leads to the formula:
 
32€ / (180W-120W)*0,20€/1000 = 2667h of service to go on breakeven with the upgrade. 
 
I usually play at least 6h a day (mostly late evening/night) and so it means 445 days of service to reach the breakeven point.
 
As stated before there are several details that hasn't a direct economic value but can change the equation results:
 
+ Single Pass Rendering for VR (even if my config with a i5-3450 doesn't meet VR requirements from nVidia but Steam says it's ok)
+ Ansel
+ 6GB vs 3.5+0.5GB of VRAM
+ Futher improvements expected from drivers (really hope so)
+ Size (which leads to lower temps of the whole config having more airflow in my SG05)
- no SLI capabilities (no problem to me having a mITX setup)
 
 
So at this point even if the performance gain is really small (if my math is correct about the gap between SSC and stock), considering this will be the GPU for my next 2 years, I think it should be convenient to upgrade (even for the saleability of the product in the future).
What's your point about it? 
 

 
From that I would say go to the 1070 or 1080.