Yaha 9ft, eh?

Unfortunately my ceiling will be about 6.7 ft

Definitely will have control of light. Do you have any ambient light in the space while watching or complete black? I've heard that it is recommended to have some light behind the screen to ease eye fatigue. I thought this would only be applicable to big screen and wall TVs.

Low lamp mode makes sense. Likely it would negate any need (if any) for any light in the room.