What about a larger screen, any benefit? Or higher resolution and lower FPS?
Larger screen is good but only up to a point. Once you increase resolution, FPS decreases, so I'd rather
"pay" for a wider FOV rather than increase resolution for details I may not notice, although some people claim 4K screens allow them to tally earlier.
One thing that can help combat the FPS decrease is running less AA. I was running 8x or 16x on most titles at 1080, but generally run it completely off at 4k, and I do generally see more details, yet still get a nice smooth image free of 'jaggies' and shimmering. I'm on a 32" monitor that sits about 3 feet away from my face. Where this really pays off is in the cockpit; I can zoom out more, but still make our crisp details on gauges and MFDs.
Still, you'll need a decent video card to handle the pixels. The only easy day for my 1070 was yesterday
Be warned, though the DCS GUI is a PITA at 4K, and the "GUI scaling" option seems to bork the F10 Map view ( a critical asset to 'cheaters' like myself
). I haven't tried in the more recent versions of DCS, but it was like that as of ~6 months ago.