I wouldn't sweat it if I were you.
The RP-8000 are pretty good themselves, so the RF7 would be rather pricey for a more or less lateral move. All the flopped over mtm style centers are inherently flawed, so no tremendous gains their either.
All the models you mention employ dual woofs, suggesting lower impedances, but also fairly sensitive, so the need for an external amp is questionable. What are you using to drive them now?