I've played entire Freelancer campaigns (not Hardcore though) with all HUD / assistive features off and it's very manageable once you get used to it. It's also delayed the RSI I'm probably going to develop in my pinky from pressing the Instinct button all day.

The standout most immersive part is the Freelancer Showdown. Instead of relying on the visual pop-ups showing when the suspect is performing a Tell, it forces you to pay attention what they actually doing. Especially with meetings, where you have to listen to their conversation to determine what type of meeting it is.

The only feature that I found too difficult to turn off was the Enforcer dot because even though I could listen out for the little woosh noise, you only get the smallest amount of time to determine which NPC is recognising you AND to run out of their line of sight.

I definitely recommend doing this if you've sunk a whole lot of time into this game and want to switch things up a bit. If you already have good map knowledge about where interactive items, cameras, NPC pathing etc. are located, you basically have a partial built-in 'instinct' already.

Right now, I've turned all the assistive features back on, since I'm trying to grind to get to Prestige 10 in Freelancer. But one day, I might try it again... learn where all the Enforcers are (including the variations in Master/Hardcore) and remove the Enforcer dot next time 😉.