Black level is the most important parameter for image fidelity.
Oh, and about THX, or at least THX video training, look here (should be public access).
I think the F8500 will do well as a replacement for my VT50 up north. The room begs for display lumanance. On the other hand, unless there are some large faults with the ZT60, one will likely show up in my FL light controlled mancave when I get back in October.