Here's an interesting article created by one of our dealers in the UK. He installed a 170" wide Center Stage XD screen, and fired two projectors to record their differences.http://www.geckohomecinema.com/1080p-vs-4k.html
The 1080p shown in the screen shots is a 3 chip 1080p DLP Runco VX44d (£80,000), and the 4K projector is of course the new Sony VPL VW1000ES (£16,800). They were fed identical material from the same player, both onto the XD screen. First, it's amazing the difference in detail from changing only the projector. Keep in mind that while the Sony's 4K may seem like ridiculous overkill for now, this incredible performance improvement is available at a fraction of the cost of the 3-chip Runco. Of course, the Runco is crazy-price, but it always makes my heart flutter when something much less expensive performs so much better.
Also, please note that the performance of this nearly-six figure, otherwise state of the art projector is not being limited by the Center Stage XD screen. In fact, the screen has so much more to resolve. Also, while the argument is solid that if you buy a quality, reference projection screen it will last through several projectors and be the best investment in the room, keep in mind how inexpensive the XD screen is relative to the other equipment.
Rob had this sage advice regarding screen selection for future-proofing your theater:
Do I Need a Different Screen?
If you have a flat white screen it will be perfect for 4k projection. Vinyl screens with acoustic perforations and some woven screens however will compromise picture quality. Where the best picture and sound quality is required we typically recommend Seymour AV screens as providing the best combination of acoustic and video performance. These screens are also excellent value for money.
The couple caveats of course regard screen size and seating distance. Their demo screen is a spaceous 170" wide 2.35 ratio. While we don't yet have a minimum size rating for 4K use on the XD, the Enlightor-4K is the obvious solution, or for when you're needing to sit closer than perhaps 11'.