thanks for all the feedback
I've pretty much decided to capture and archive in 4K. For the videos I want to watch on the TV, it's easy enough to down-convert to 1080. And while the cheap GPU I have in my PC won't really process 4K, it's still pretty easy to cut out unwanted sections and join videos from specific flights using AVIDemux...then archive
if I wanted I suppose I could even use DaVinci Resolve (thanks 66427cobra) to adjust colors and contrast with the 4k, then archive
I know we'll be getting a 4K TV in the next couple of years (I'm already lobbying my wife but it will be a long process). At that time I imagine I'll be really happy I archived the 4K