First, I must give Props to all Mentors out there. You know who you are.
Second, In my Humble Opinion. You will probably lose between 8 and 12 lbs of pressure from the static pressure by using an RP. Hopefully you are starting with over 60 PSI.
What are you starting with?
As Stated Earlier not much difference between 3/4 and 1"!!!
8 to 12lbs is 8 to 12 lbs.
Hi.todd