I don't want to make a statistic based on anecdotal evidence, but I have a VW50 that clocked over 8000h, going on my fourth lamp. I don't have any deterioration of the blue polarizer you have, so it's not a problem inherent to this model, nor a problem with sxrd panels.
Your mention of the optical block being burned to ashes is a good indication that the optical block was overheating way out of specs. It could be a worn out fan bearing or bushing, an obstructed or dirty filter, a failed temperature sensor, or something else that cause the block to overheat. That's what you need to find out first if you want to repair it. If you don't diagnose the actual cause of the problem, you will have the same burnt parts later.