Yes my integrating sphere is the guest bathroom with a big mirror and no window. Lumen measurements are overrated (said the guy who couldn’t measure lumen :innocent: ); plenty numbers available.
Kidding aside I do use “pro”’s reviews to check my values, like the recent excellent TS30S review by Luxwad. (And conversely, use my measurements to check theirs to make sure no one drops the ball. 
)
For example Luxwad’s turbo start brightness is 4500, and stepping down to 600-700. My stepdown percentage for my TS30S was 16% using ceiling bounce.
