Is Goenka's "Freeflow of sensations" the same as pīti? In the S.N. Goenka vipassana tradition the meditator tries to reach a 'freeflow' of sensations on and in the body. Is this 'freeflow' comparable with Pīti?
Yes.

Free flow is loosely used for Piti. Initially it is subtle vibrations which you feel. As you practice this spreads to your body. These vibrations are pleasant.