I was just answering the question about what snags stuff. I'm not sure how much of an issue door handles and bannisters are for slings, I just know they snag sleeves, backpack straps and bag handles on occasion.
As for me personally, I don't have kids, so my only issue is one conjunction between several rooms, a hallway and the stairs. I have tried a couple of things and just didn't see how a 30+" rifle would be advantageous in the tight space. Since I don't own an AR, I didn't bother to buy one. I also watched and read as much as I could about using a carbine in close quarters, and never saw anything that really dealt with what I was seeing.
Carbines with slings are the single most effect CQC tool going because they are the most effective in the largest number of circumstances. That is not the same thing as saying that a carbine is the best solution in every circumstance, or that a slung carbine has no limitations over unslung. This thread is about the intersection of generalizations and specifics, since we are talking about our own homes, not homes in the abstract.