For anyone interested, I hooked up a laptop and tested the number of local dimming zones.
12 across
8 down
This is less than I thought, but equal to the LG LH90. I'd assume this is why the Toshiba is priced so much less than the Samsung 8500, but whether the number of 8500 zones is worth $1700 more is unknown (as well as the number of 8500 zones).
They are laid out in such a way where letterbox and side bars are just about as black as the bezel.