Would anyone object to it if it was wired like this?
1) Fewer current carrying conductors in a pipe for de-rating calculations
How about a scenario of derating in a metal wireway or auxilliary gutter?
Up to 30 conductors in a cross section, derating isn't required. 31 wires in a cross section will require you to derate all of them to 40%, and quite possibly require a larger wireway.
I've never done this myself, but I can see where it might have some applications.