I'm not sure how this interacts with power flow though.
Experiment: removed logistic pipe (with power transfer upgrade) that delivered items and power to and from my auto-crafting machinery in the south quadrant of the base. It was a corner junction that also received high volumes of items from a tesseract.
Result: Power continued to be delivered to all machinery*. Items entering the warp itemducts from the tesseract were all delivered to the default route, despite the default route being the only logistics pipe they came into contact with.
My empirical evidence indicates that itemducts (at least the warp variety) act like they possess power transportation upgrades, aka they route the power lasers places; additional tests revealed that this is only the case if there are less than four logistics connections on the itemducts. Further tests are planned to explore this (I would have thought it would have a max of two, but with three power is still delivered)
In addition, items entering the itemduct from a non-logistics connection appear to be routed to the correct destination automatically. further tests are planned to determine if they are simply being delivered to the closest location, or if they are actually being routed.