At my school, they only required that you had been involved in FR either on the PNM or the sister side. After I was a Rho Gamma, the next year they changed it to be only those who had participated at least once on the sister side. So I only did FR on the sister side my senior year! And I gotta say, I much preferred being a Rho Gamma. I don't consider myself a good rusher but I do very much like to help people figure stuff out and I consider myself a good listener so being a Rho Gam seemed like a natural fit for me. At my school, most girls would rather get out of FR on the sister side and go neutral so it was rather coveted since you had to go through interviews with Panhel and such - I even put my acceptance letter in my Zeta scrapbook
Maybe Panhel made it seem like an honor for a reason now that I think about it.... whatever, I liked it