Hmm, as far as 2 and 4 are concerned, I find the yellow snow and green sky on the blu-ray pretty questionable myself, I personally feel the colours in those scenes look much better after the strong blanket yellow tint has been removed.

I think 1 especially is a big improvement, the blue of the lightsaber and the core in particular look so much better on the regrade IMHO, hot like the lightsaber cores in the other Star Wars films.

5 is the only shot from the blu-ray shots where I don’t consider the regrade a big improvement, both shots look good colourwise, the regrade looks more natural but the blu-ray shot looks good as well.