I bought the DC, flew out of the station and came back in to use it. It seems there's no manual override option, i.e. if it's installed it's live.
In my Sidewinder it was broadly aligned to the letterbox, then did a spinning move at zero speed, probably going around 4 or 5 times. I can only imagine this was fine tuning the approach.
Went through at 30/40 speed. Then hung inside the station, did another ballet dance right in front of the letterbox (my fear being hit from other ships). The only fast bit was once it spotted the bay and got down very slick and quick.
I immediate sold the DC.
I'd like to be able to toggle it on/off even when installed.
I can see advantage for landing larger ships but only IF it knows it's a larger body.
If it's the same AI as the NPCs on landing then I'd not want to DC until the AI is vastly improved to stop dithering.
The other option is a 'fade to black' at 1km out, and a fade-up once on the pad, but not sure how well that works with multiplayer.