Yes I do as my winter bike – the sealing is pretty good. It does need maintenance every couple of years, I’m fortunate that my LBS is good at stripping and fixing them.
So I got this one S3X

Aren’t they generally 130mm OLD rather than normal MTB of 135mm?

Some old pictures. The one of the bike isn’t with it fitted – just showing the best cable run / cable stop position if using an old tube nut rather than all that plastic / cable guide gubbins:-

As you can see, the spacer nuts and “freehub” design mean that the chainline is a long way inboard (make sure you can adjust chainring far enough inboard to get it to line up).

Why not use an alfine 8
they are pretty cheap, not much heavier than a SA, bombproof and impervious to mud.

I take mine down DH runs

I think all the 3 speeds are pretty close in terms of ratio range – I once worked it out to be somewhere near equivalent range to a single rear sprocket run with a triple chainset.

I personally prefer the pedal “feel” of the 3 speed to the Alfine (very subjective). Alfine 1:1 is spin most cogs in the box, whilst 3 speed is locked out and fully efficient apart from energy losses of a ticking pawl 🙂

Alfine is silent. All 3 speeds (inc Shimano “silent clutch”) go tick tick tick as you pedal certain gears.

As per my photos – there are no seals at the bearing cones – just shields. That black cap between the “freehub body” and the hub shell is just a tinny clip on shield – remove it and can see the edges of some balls. There is also a hole down the axle centre that goes into the hub. For road and summer use it is fine. For typical winter mtb duty cycle of immerse in mud – occasionally hose off – stand for a few days to corrode – repeat, it isn’t ideal. Frustrating as SA could easily add some good seals. Many years ago I swapped some emails with Alan at Sunrace regarding making an MTB specific hub. That was before the disc mount hubs came out – maybe time to ask the question again