I just came back to this thread to correct myself, I went from Cascade 1200 to xp3, not an xp4.
Which is pretty close to an apples/apples comparison. The cascade I had was pretty old, came with the tank. (which was free and sitting in someone's back yard half full of rainwater.) simplistic flow rate calculations put the cascade at just over 100gph, so even figuring in a 50% margin of error It was still only operating at 1/3 of its stated GPH.
Still, in my experience, the Rena is smaller, quieter, has more configuration, and is way easier to prime after cleaning.