People generally sit far closer to a monitor than they do to a TV so the eye can resolve imperfactions more easily on a monitor as the eyes ability to resolve detail is a function of distance.
As psycik said, essentially your question is whether the TV is better at upscaling than a graphics card.
Basically you need to test it out and see for yourself as there there are too many variables for anyone to offer a definative answer to this.
I am still on 1080p so not qualified to offer any experience of 4K but if you have a fairly recent g/card, I would have expected the card to be better at upscaling than the TV but that depends very much on the specific card and the TV. I would always run my g/card at the TV's native resolution and as you say, you can then run apps such as Netflix in native 4K.
One potential concern is if upscaling via the graphics card puts a high load on the card, this could drive up it's temps and fan speeds, making it noisy.
The MadVR renderer is supposed to be the daddy when it comes to upscaling but sadly NextPVR doesn't support (ie work) with it due to problems with the on screen display (if I recall correctly).
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