I know that a projector's overall picture quality is VERY subjective, but I'll tell you my thoughts on this prior to receiving my new 6800 tomorrow.
I've owned a CRT projector (Sony VPH-D50 for 10 years), Mitsubishi HC5000 (2 months), Epson Pro Cinema 1080p (1 year), and Panasonic AE2000 (2 years).
I like to think that I know something about video projector picture quality after owning so many different models over the past 14 years.
I can tell you without a doubt that my favorite projector was the Mitsubishi 5000. Why? Basically, it had the sharpest, most detailed picture without having a "digital" look. The reason I gave back my 5000 was because of the infamous "banding" issue that plagued early models.
Ever since, I've been trying to get a picture that matches the 5000 and both later purchases have come up short. Basically the reason is that if the 5000 had a sharpness dial that went to "10", the Epson only went to "8", and the Panasonic went to "9". That extra sharpness made ALL of difference to me.
Since my HT is also my living room, I can never get a completely dark room. I can tell you that the Contrast Ratio and black levels of the 2000 were completely satisfying, and the 6800 will better that performance in all probability. A lot of the bells and whistles that the 4000 has are really of no interest to me. The 6800 seems to have all of the extra features that are important to me (Motorized focus, true "blanking" (not overscan adjustments), a fast, quiet Dynamic Iris, almost totally quiet operation, etc)
My bottom line is that I'll bet the 6800 at $2499 will give me a better, more satisfying performance than the 4000 will at $2000. Hey, $2K+ for a video projector is not chump change, but compare the performance I'm likely to get with the 6800 compared to my $9K CRT projector, the price/performance ratio of today's projectors is almost miraculous!
I guess by 10 PM tomorrow I'll know a lot more