Honestly, I would rather have the Panasonic ABL with the bit of a darker picture (that will be less noticeable in home not beside the 8500) then have the 8500 with it's ABL and constant brightness pops that are quite noticeable at home with no other tv around.
I owned a VT50 and a F8500 and the 8500 was worse, couldn't stand the brightness pops. That tv was sent back after a week of having it and I only used it once. Couldn't stand the pops and went back to my old plasma/CRT tv. That's how bad and annoying that was. Now waiting on a ZT60.