I have own the D1X for 6months now. The one issue some have is the older tech. batteries. Personally I didn't bother with the Nikon batteries but have bought the batteries from BatteryBarn. Great price, service and warranties.
Image quality is fantastic with the colors and rendering as close to film like (Velvia) as anything I've seen.

I use Nikkor 17-35f/2.8, 28-70f/2.8, 70-200f/2.8, 85f/1.4, 50f1.4 and they all do fine.

I regularly make A3 (13X19) prints which are beautiful and wouldn't hesitate going much larger.

One thing. Viewing an image on the LCD will make you feel like the shot is garbage but trust your abilities and the D1x as when opened up they are simply stunning.

Focus is fast and accurate with any lens, AF-S or screw. The meter is very accurate.

These may be of an older generation but those of us that use them love them.