I think you highlighted some pretty good points. And regardless of where people "fall" in those categories, it's supposed to just be a general guide to show people the common opinions on this forum, and which among them are the most outspoken. A warning tool, if you will.
If you're looking to create a guide to the forums, I recommend looking into two other fields, which are console vs PC and the differences between speculations, suggestions, and demands.
Immersion is quite important to feel like the gameworld is believable, to feel like you're there, but in the gameworld (stay with me here) you aren't RL you, you are a different you, had you been containing different properties, and characteristics. You can parrallel it to an actor and there role, two actors can play the same role, but the way the role is expressed is different based on the actor, even though the actors are playing the same role with the same characteristics.
I do think that Immersion and hardcoe Roleplay somewhat cancel each other out. I mean, there is an achievable level of balance, but it's impossible to perfect one without ruining the other. I don't think a hardcoe roleplayer can feel immersed because of the fact that they feel they are playing someone other than themselves. It's like going to a movie. You can really get into a movie, as in it captures your attention and there is an emotional bridge, but you can't delude yourself into thinking that you are
in the movie because the actors do not behave as you do. Immersionists don't think about "What would a Khajiit Thief do in this situation?", they think about what
they'd do, and the character is an extension of themselves. As a hardcoe RP-er though, where you make the character do the things you yourself wouldn't do, that brings you out of Immersion because you are reminded that you're playing a game. For instance, though Mass Effect was a phenomenal game and one of my favorites, it was hard for me to be immersed with it because I wasn't me, I was Shepard. The game limited things you could say and do, which forced me to say and do things I normally wouldn't. It had a set storyline as well. You couldn't be Shepard, janitor of the SS Normandy. You
had to be Shepard, savior of the galaxy. In Elder Scrolls, though, I can feel free to be Rolf, slayer of mudcrabs, and I don't give a damn about saving the world.
On a different note, relating to character roles, RP and Immersion do share certain common beliefs. That is, not restricting the capabilities of characters. Neither Roleplayers nor Immersionists want to be limited in what they can do. If I myself would handle a situation in this way, but can't, that ruins the immersion. If the character I'm controlling would handle a situation in this way, but can't, it ruins the roleplay. The main difference between Roleplayers and Immersionists is player skill vs character skill. First-person or second-person. Dynamic or spreadsheet. Skills and capabilities are reflected through those, which is where the differences come from. It's not black and white, I should say.