Good summary and same or similar experience here.
On black ice or slimy snow over a glare ice layer, I'll do slippery, or most often Normal with nannies depending on the traffic, or steepness (exposure) of the mountain logging road. I basically hate the muted simpy beta nannies and/or slippery mode, but it has a place in the toolbox of options.
If I am not getting after it and the roads aren't too slippery (aka less wheel spin), 4A is fine with or without nannies. If it is slipperyer than that or I am pushing the truck more, it is too much to ask of the 4A. Not that it has a lot of lag, but why put all that slippage and compensation through the system when you could just be in 4H and know what you got.
As far as the locker, I've played around with it on and off. I has it's place but being open in the back has advantages too. Without going into detail, it's something I'm still figuring out. I know the local jeepers who are on like 40's + 2psi who do extreme snowwheeling swear by open diffs for most of what they do.. it digs in less. Granted, they are light and are trying to stay on top of the snow, so not totally portable to a full-size on 35s.
I generally use N or Deep Snow and nannies off as my Rx for most snow conditions on and off trail.
Mostly in the snow - I am a shark among seals. Seals that can still slide into you... so head on a swivel. But still.
As far as psi, it depends on the snow. If I am trying to cut 'through' it down to traction 32 psi or more. If I am trying to gain traction over slimy ice etc., then 24 psi and lower. Since a lot of where I go is mixed speeds and traction, I just run at around 25 psi and it covers the range for me most times.
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