Everyone else pointed out some good stuff as well!

@ Spaced Ranger
In terms of encoding 8bit to 10bit and playing back 8bit, it really depends on the source and how far you are compressing. Encoding from the highest quality source is crucial. Other than the new 4k blu-rays, I’m not aware of any other high quality 10bit source available to the general public.

I tried to put together a quick comparison here from the movie Saving Private Ryan; granted, this movie is probably a worst-case scenario for good encoding at small file sizes, but still (45GB vs. 7.8GB) is not too bad. Most of my encodes are right around 2GB and still look extremely good compared to the blu-ray.
http://screenshotcomparison.com/comparison/175765
As well I hope you checked out the short x265 clip from DeSpecialized 2.7 in my last post.

The main benefit I see from encoding a blu-ray source (or other high quality source) to x265 10bit is the small file size while maintaining at least 90%, I’d say, of the original quality.

It also depends on whether the movie has a lot of action or whether the camera moves a lot, as well as similar colors throughout a scene.

I’ve learned a lot already just reading through this page.