You can turn it off, but I do remember it getting 'stuck'. I think I changed modes, turned it off and switched back. I don't use any of the things you asked. Here are some 6500K calibrated game mode settings.
http://www.neogaf.com/forum/showpost.php?p=224843451&postcount=1568
Cool thanks, I was able to get backlight unstuck! I ended up making some changes. Mainly backlight needs to be higher for me because Rtings I believe tests in pretty much a pitch dark room to hit that 100 nit for Sony's in a dark room.
If you have any ambient light in the room you're going to want to be closer to max backlight.
Also I've found that changing color space to rec 2020 improves colors in HDR PS4 gaming (uncharted).
I think Expert 1 looks better with Color at 60.
I've found that the black adjust does not seem to do much of anything, but I think that medium adaptive contrast while HDR gaming dramatically improves contrast without crushing, at least on the IPS 49x800d.
My settings for HDR gaming on the 49X800D IPS:
Picture Mode: Game
Auto Picture Mode: Off
Light Sensor: Off
Menu: Advanced Settings:
Submenu:Brightness
Brightness: Min if in near pitch dark room, Max during daylight, 30-40 if you have other lights on in the same room as the TV at night time.
Contrast: 90 (if you go higher than 90 the whites get clipped in uncharted brightness slider, even at min brightness in the in game slider).
Gamma: 0
Black Level: 50
Black Adjust: Off
Adv. Contrast enhancer: Medium seems to dramatically help contrast and blacks without crushing on the IPS model
Submenu: Color
Color: 60
Hue: 0
Color temperature: expert 1, or warm depending on your preference. Lean towards warm as expert 1 sort of seems to put an unnatural reddish filter over everything. Warm is a bit cooler but not overly blue. Rtings would suggest expert 1 and if you like a warmer image go with that.
Adv. color temperature: Do not have any 49x800d reference points to do 10 point color adjustment so just left this as is.
Submenu: Clarity
Sharpness: 50
Reality Creation: Off
Submenu: Motion
Motionflow: Custom
Clearness: Max
Submenu: Video Options:
HDR mode: Auto
HDMI video range: Auto
Color Space: Rec 2020 while playing HDR games, 4K HDR blu-rays, or HDR streaming content. Otherwise Auto.