Considering Saber's stats and special ability would she get a slight boost in power riding Centorea (or would Centorea get a boost)?
I know it wouldn't be on par with Rider's powerup, but it's still fun to imagine.
They would both get bonuses I think. Saber had a rank in riding (B or maybe even A, not sure) while Centorea is all about serving a noble lord. You don't get more noble than Legendary King.