I see clue 6 as a variant of clue 5 where there is a list of elements that aren't the same person.
In clue 6, there are three elements in three different categories, so that should produce 3 Xs.
Many of the new puzzles have clues of this form.
In my opinion, this puzzle is tough because it requires repeated application of the more advanced deductive reasoning techniques. I like the new puzzles added in mid-December because many of them look so utterly hopeless after the first pass through the clues and then finally yield.
Thanks for verifying the solution.