I don't have the data handy but i believe that the durability of negative 12 wk EOT vs negative 24 wk EOT( which i know as SVR ) is significantly different.
True of ifn + rib protocol. But might be different under different protocols - e.g. I believe that prior to the use of rib (i.e. when ifn monotherapy was the primary treatment for HCV) SVR was 12 week SVR. Presumably because the relapse rate after 12 weeks was negligible.