Is there any advantage on using a low span value in a RRC filter?
The advantage of a RRC filter with a smaller span is that it has fewer taps, so the filter requires fewer multiplies and additions per sample.  Longer filters approximate the ideal RRC response more closely but require more computation.  Shorter filters do not approximate the ideal RRC as well but require less computation.  Typically, one will choose a filter length that strikes a balance between computational demands and performance.