I currently have a RS-PS4 and am looking to upgrading to a PS6 or PS8 so I can get some additional relays for some automations I may want to do in the future. The PS4 is basically brand-new and under scoped from the PB so looking to see what would be involved to swap this out to a PS6 or 8. I was looking to buy one off eBay but not sure exactly what I need. Do I just need the PS8 control board or do I need the CPU board also? Also which revision should I be looking for? I do have iaqualink 3.0 also.