Yes it would be a crap move, but Marcone has a blindspot for pettiness where Harry is concerned, something Harry can exploit.

Which he would, I can see Harry ridiculing him in public on that very point..

Another thing to consider is time. It seems to me that if you soul gaze someone who's 20 years old, and see that they're idealistic, optimistic and has lots of potential, decide to trust them, you can't fall back on that assessment 10 years later. People change all the time, and you can't gaze them again. You still have a very clear memory of the first gaze, even if they are a completely different person at 30. (which is very likely), so if someone else gazed them and found a dark and cynical soul, you'd unlikely to belive them.
I think it needs a rework in a future book.

People do change especially the young, but that is why when Harry describes his soul gaze with sixteen year old Molly, he describes her possible futures, the trick is judging which future will be the most likely.  Then one has to decide if intervention will help or not.  Harry judged that Molly wasn't too far gone, though in reality given her slip ups that that was a very close call.. The Merlin on the other hand judged that the Korean Kid had gone too far down the tubes and his future was bad no matter what was attempted to redeem him.

I think the iron has to actually pierce his skin.  Do that, and it disrupts the Mantle entirely.

Simple contact isn't a problem for the WK -- he is still human, after all!

I agree, there was also the bit at the end of Battle Ground, when Harry was picked up off of Demonreach and they almost killed him treating him for hypothermia, which because he is the Winter Knight he didn't have.

  Or if you go back to the original Star Trek that gave Jim the idea for Mirror Mirror, to be a strong leader a person needs both sides.. Harry's Id is much more his dark side, he is more assertive and doesn't seem to have much of a conscience.

As for the rest, I really feel like you're stretching the extent to which Id!Harry is his own entity and not just Dresden being a bit loose in the head and having existential dream talks with himself.

In a sense the Id,is his own entity, lets not forget back in Fool Moon I think it was when we first meet him, he is a very different Harry from the one we know.  I wouldn't be shocked if that is the Harry we meet in Mirror Mirror..

And then do a replay in White Knight. Have Lash decide the best way to keep the taste of freedom that she's found is to let the curse burn out the parts that tie her to the Fallen. She gets put into the real world with a darling skull of her own. That is one way of affecting reality.

That is a possibility, but while Bonnie may really be Lash, she isn't Lasciel's Shadow either.

We have no reason to believe that Michael was wrong with the exception of Harry. In Harry's case the Shadow was supposed to be burned out. This doesn't prove that Michael was mistaken. It's used as a plot point to drive the uncertainty about Harry's allegiance in Small Favor.

Yes, Michael's doubts or claim that it had never happened before was meant to keep us in suspense. However with the gift of Soul Fire from Uriel, all doubts were done away with.  Here is one for you, seemingly in contradiction, what if Lash, then Bonnie are really Lasciel as she was before her fall?

If you control the mind you control reality. Try this on for size.  If you are  Lash and you are ordered to wreck LC, all a shadow need do is alter the reality of what her host sees and does. Have the host tell Bob to not see it and there you go. And you thought you were ordering steak at the steakhouse.

That wouldn't be a shock since the Shadow of Lasciel convinced Harry's mind that he was seeing a woman named Shelia and if it weren't for Butters convincing Harry that there was no one there, things might have turned out very differently.

The kitchen fitting are left from Marcone, he knows Harry is the Winter Knight and may have left them deliberately, knowing that Harry would be affected to some degree. The walk in stainless steel fridge makes a lovely Fae trap. It would hamper even Mab.

If so I wonder how long Marcone mused on the regret that the toilets weren’t made from the Bane? There is no proof of this so I have nothing to go on. Unlike Harry.

Are we really sure of that though?  Nothing said about it in the books, and even if it was, it appears that Harry isn't having it changed to accommodate his pizza loving army.  In the over all expenses of the castle remodel job, switching out the fridge, freezer, sink and counter for another material, isn't that much, Harry doesn't need a huge kitchen.  Apparently since there is frozen pizza, Harry has figured out a way to live with a modern freezer.. Because an ice box isn't going to keep pizza frozen very long, yeah maybe since it is still winter in Chicago, but not long term.

Apparently the "bane" or stainless steel doesn't bother Harry, so bane toilet seats is kind of a moot point..