Source quality will of course have a huge impact on the quality of the gradients. Compression especially can cause severe color banding and artifacts. Handbrake, VLC and Plex all have built-in dithering filters to help reduce color banding, and they work well. 8-bit content will never look as good as 10-bit content on a 10-bit display, but with good dithering an 8-bit panel can look almost as good if not better than some 10-bit panels.