Those are actually my two most recent demos. I like both.
Gravity Pro - more stability, great pop on serve, good spin esp for 18x20, larger sweet spot
Phantom 97P - whippy, less pop on serve but easy to place, very maneuverable
I don’t play a one handed backhand, except for slice, so no feedback there. Both demos had dead feeling strings, but the Prince demo’s strings were just terrible. This definitely took away from both demo experiences, but I’d say I liked the Gravity Pro more. I play a blade v7 right now, and I’d consider a switch if I could get a few matches in with the Gravity Pro and they went well.