I've had the 6800 for two years now, and it is by far my favorite LCD projector (prefer over Mitsu 5000, Panny 2000). To my eyes, the blacks are good, but the picture overall is supurb (smooth, sharp, great color, bright).
I have my fan on regular and it is very quiet. The auto iris is OK, I have it at the lowest setting and I never see it working during an actual movie.
I plan to keep this baby in my theater for at least another 1-2 years.
Receiver: Marantz SR-7011
Projector: JVC DLA-X550R
Display: LG OLED65B6P
Sources: Oppo BDP-103; Samsung UBD-K8500; Cisco CHS 435HDC (FIOS)