One problem with dropping ducting from the ceiling to a slider in the middle of the room is the location of the drop will still get in the traffic lane. It probably needs to be at least 4.5 feet to the right of the blade. The duct run can't be in front of, to the left, or behind the blade.
If you have a combo machine, it seems like a vertical drop would end up right where you would stand for the J/P operation.
Please share some pictures of your ducting to a combo saw/J/P.