She's not really much like Rainbow Dash IMO, aside from both of them being athletic. Zipp is an analytical introvert, RD is a rash extrovert. Pipp is more like Rainbow Dash. She loves attention, she's self-confident, she has her own fan club, and she wants to be recognized as the best at what she does. I mean, it's not one-to-one, but they share more traits.
But anyway, yeah, I love Zipp and her family. The contentious relationship with her mom, her struggles to understand her sister and vice versa . . . Great stuff. "Zipp's Flight School" is one of my favorite Tell Your Tale episodes. Baby Zipp learning to fly parkour!
A nice design element is that Zipp has silver hooves while her sister has gold hooves. Pipp is the golden child of the family, even though Zipp is the heir to the throne.