REALLY need help understanding/picking out a monitor!

[mebcitadel]

So I was going to get an Acer XB270HU because it's essentially the latest and greatest tech except for 4k. That's actually my reservation though, If I spend $800 on a monitor I want it to last a solid 4-5 years and still be "decent/average" at that point in time. I feel like we're at the sweet spot now to where a large expensive monitor is justifiable, much like when 720p/1080p came out. I had a 1080p monitor from what seemed like years ago and I am still using 1080p and only just now really wanting an upgrade.

My question is that considering the advantages of g-sync, wouldn't it be more wise to just get a 4k 144hz monitor (or wait for one if they dont exist quite yet) and then use it until my pc hardware catches up (780 Ti right now, but I could scale down the resolution on the screen to 1080/1440p right?)

I guess my questions are this:

If I get a monitor with ONLY displayport will that really limit me in the (4-5 year) future?
If my monitor is 144hz does my pc have to be pushing that refresh rate to make it worth it or will g-sync pick up the slack and I'd be getting, say, 60FPS until video cards can handle 4k better?
is there a drastic enough difference in 27" from 2 feet away between 1440p and 4k to even care?
And how does a Titan X handle 4k with ultra but NO AA ( i think thats totally redundant)

and LAST question:
Can a 4k monitor scale down to 1080p/1440p and look ok/the same as an actual 1080/1440p monitor? Because if it can I don't see the point of limiting yourself

 

[manofchalk]

DisplayPort would be far less limiting than having a monitor with just DVI or HDMI, so of the options its the best. Anyway, GPU manufacturers have been trending toward DP for a while now and with both AMD and Nvidia investing into DisplayPort technologies (Freesync and Gsync) I don't think support for it will be dropped anytime in the foreseeable future.

To my understanding, you really get the benefits of a >60hz monitor once your pushing above 80FPS, even top performing cants cant reliably maintain ~120fps at 1440p/4K. GSync will probably make up for a fair deal of it anyway.

I cant really say, I dont have a 4k monitor.

Like this (not the exact settings your after, but you get the idea).
https://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_Titan_X/8.html
There is also something to be said that if a Titan X doesnt perform to your standards, then pretty much nothing will.

A 4K screen can scale down to 1080p perfectly as 4k is really 4x1080p (like 1440p is 4x720p). However I think you should run at native res no matter what, more pixels will always look better than the difference between High and Ultra will.