Grass/Gravel/Snow is really best for compact snow & ice....I still turn HDC off though, because I've had HDC induce a slide in the past. Engine braking in low range is more than enough.

My go-to setup while off-road is:

4-Lo
Mud 'n Ruts
HDC on
DSC off

That will do fine in 95% of what we drive in up here in the Pacific NW. I use Rock Crawl (all else the same) when I'm driving over large rocks, sand for sand, etc. I use that baseline setup in deep snow, too.