You also get NPC Belugas (and other ships) stuck in the slot...
As for boosting in (or out) of a station, some ships are driftier than others. Boosting at the slot going in, though... nope, the boost will still be building when you smash against the rear wall. Some ships may survive that collison, though, but that's not exctly what you'll be aiming for. Most small and medium ships you can go through the slot at full speed, then throttle back and not impact on the rear wall. Since I've been checking it (for collecting mats) these days, with deployed cargo scoop, my Krait takes ~500 meters from full throttle to standstill. The station is something like 2000 meters deep.
But yes, going through the slot with an iCourier at 700 m/s is survivable. If you don't run into any ships, and especially if those ships survive the impact.
On outposts, you just have to be fast - on the other hand, system security is very rare there (I'm tempted to say nonexistant). Ground bases, on the other hand, are more challenging. They do have patrol ships (you can check their comings and goings in the comms - sometimes). But: slamming a ship onto a pad does much less damage than slamming it onto the planet's surface, so as long as you hit (and stay on!) the pad, you're reasonably safe.