The 4910/X500 has basically the same native contrast as the entry RS46/X35 which before being discontinued, was about a 1/3 the price of the Epson LS10000. If spending $8,000 on the Epson, it should be able to at least match the contrast performance of the entry model.
regarding the 4k shift, opinions will vary widely since there is image processing involved. Someone's idea of 'sharp' could be way overcooked (remember how people were going nuts over the reality creation on the HW50). I'd like to see if the projector can resolve to the pixel level with the 4k shift turned off. How 'naturally' sharp is it?
3D is a topic into itself, cine4home does not post the L/R patterns. The details are usually very technical, more-so than any other review, but it's still hard to gauge the 3D performance without the screenshots through the glasses like we've done on the shoot-out threads. It's the 1 time a screenshot can actually count for something.
The X500 is 1/2 the price and the difference in cost buys ~12 lamps. Each lamp turns it into a 'new' projector again which helps with resale and rejuvenating screen brightness. I'd like to know if I use the Epson LS10000 with high lamp all the time (big, low gain screen or 3D lover) how long will the laser last until 75% and 50% of it's original brightness.
DV - you sound interested, i think you should buy one and give us the full report. Can it handle the 3D processor with x-talk free images? Those L/R reports would go a long way..