Active HDR/Dynamic Tone Mapping?

[tama]

So I recently purchase the Panasonic UB820 for the benefits of the HDR Optimizer. It's been recommended to turn off the DTM/Active HDR when using the Optimizer which make a difference for content mastered in 4000 nits but not with 1000 nits.

So with 1000 nit content does Active HDR do anything besides brightening up the image? Do professional calibrators recommend turning this function on or off?

The TV will tone map regardless with Active HDR on or off but starting to wonder if this was a useless function.