I have read the degree is a relatioship between CPU utilization and disk drives.
What is your average CPU usage? <=30% then go for it, > then think about add more CPU.
If your table is in only one disk PQO will increase the contention on that disk.
A very good combination is Partitioning by range (fewer records) and subpartitioning by hash (spread in disks) with parallel degree=d*p where d=disks & p=processes running in each disk.
Hope it helps.
I drop PQO because a horrible bug in Datawarehouse.
We are planning PQO as I said in Billing system (huge)