I actually have the Sony vw1000es 4K home cinema projector.
The Star War's blu's(both prequel and original) look absolutely phenomenal on it.
But.....
Due to the increased resolution offered by the projector....(all be it upscaled) the limitations of the analogue techniques used in making the OUT are far more pronounced.
In particular , scenes and shots which where optically composited exhibit noticibly softer looking images than 1st generation material.
4K(and to a lesser extent 2K) is ruthless in exposing these discrepencies.
By their nature large portions of the original films featured such material.
A 4K master and a 4K Digital Cinema Package(DCP) may be too "harsh" on the OUT .
One of the reasons why Lucas opted for a 2K master.
And Lucas is not the only one.
Bob Gale said that Back To The Future(another film featuring optical compositing) was mastered from a 1st generation Interpositive for the Blu Ray release in 2010.
The original Superman films have also been scanned at 2K resolution from 1st generation interpositives.
Not because studios are trying to save a few bucks....but because 2k is good enough and scientific studies have confirmed this.
Blade Runner gets alot of hype for having been restored in 4K and is wrongly compared(by Zombie) to Star Wars.
But Blade Runner's release package was downrezzed to 2K for distribution for the 25th anniversary in 2007.
It was never projected in native 4K
(i.e it was a 4K master downrezzed to a 2K DCP and then upscaled on a 1st Generation Sony 4K projector----which few cinemas had back in 2007)
It is also worth noting that the distinction between 2K digital cinema projection and Blu ray is not that great.
2K projection is 1080 vertical X 2048 horizontal
Blu ray is 1080 vertical X 1920 horizontal
A miniscule 6 % difference.
Th only real differences are not in resolution......but in compression.
The average DCP is estimated to be 250gb....blu ray maxes out at a compressed 50gb
2K projection also has slightly higher colour bit depths.
Just to make things more convoluted....an uncompressed 2K file maybe better looking than a compressed 4k file.
So resolution is not the only factor in delivering a good all round product.