I have the Oneida V3000 and trying to finish my ductwork design. If I use the Pentz spreadsheet I think it is telling me I need to drop down to 6" pipe for the vertical drops at each machine even if its at the end of the run and I could stay at 7".
My longest run ends up at 28' with 4 90's (2 - 90's and 4 - 45's to get up the vaulted ceiling) and 1 - 7" lateral wye.