My local sorority was in existence for two years before we became a chapter of AEPhi.
The first year, they were not allowed to participate in FR. They were allowed to have an information table where PNMs could stop by between parties, chat with a sister or two, and get a rush schedule. They then held rush during the week after FR. (That was when I pledged

)
The following year, we were allowed to participate in FR, and chose to do so. BIG MISTAKE. There were only 10 of us vs. 75-80 sisters in each of the NPC chapters. Can you say double rushing?? We had next to no budget compared to the NPCs. The NPCs had built up stores of supplies and decorations over the years; we were starting from scratch. The NPCs had their nationals behind them; we had, um, let's see... one alum. We were the only local. We had only a handful of PNMs at pref, and they all matched elsewhere.

All that time, effort, and money for nothing.
With our small size and our personality, we were much better suited to COB.
My chapter has gotten better at FR with the help of AEPhi's nationals. The first year that we participated in FR as AEPhi, we doubled in size.
Bottom line, if your local is offered the chance to participate in FR, think carefully about accepting - especially if you are young, small by comparison, and/or don't have a lot of money. On the other hand, there's no reason that a more well-established and larger local can't "hold its own" in FR.