Great question. @jassnip and @decastell have already give you great advice, but I just wanted to add a bit as I've been thinking about this a lot since learning Dramatica.
Initially (months or a year ago), I was thinking that you should stay away from showing scenes from the IC's point of view, or if you did, you should focus on the IC's OS role and not their IC story points. But I don't feel that way anymore.
I read a superhero novel recently that, just like you stated, had scenes from the IC's point of view and showed her personal issues and everything, yet I never once doubted that she was the IC and the other principal character was the MC. Partly because of how the story was setup from the beginning, and what the story was (a male-oriented homage to the '80s X-Men).
I'm also pretty sure there was only one storyform in that book (X-Generation #1 by Brad Magnarella).
I think readers are simply mature enough to accept that they can temporarily be in the shoes of the IC, even reading the IC's thoughts around the issues that drive her to influence the MC, but then when that scene ends and they pull back to the bigger story, they can ignore the "personal" nature of those thoughts and feelings. They can take what they learned from that scene and re-orient it to a You perspective, and doing so doesn't take away from the experience of the story. But I think that requires that the Author understands (at least subconsciously) who is the MC, so that in the big grand-argument picture they communicate that, like @jassnip said.
In the novel I'm working on now, I'm writing scenes with the IC's POV, and really enjoying them. I sort of feel like the IC is a bit of a "black box". She has personal issues and I can mention them and show her thoughts and feelings in her POV narration, but there is a level of depth that I don't need or want to go to. There's an ineffable, unknowable quality even when in her shoes. I think her personal issues are personal to serve the storytelling, but not so personal structurally, if that makes any sense.