Well unless Naruto attacks with a force enough to take down Sasuke's PS, it doesn't matter whether he uses RSM or Bijuu mode. All that matters is the attacks he used directly against Sasuke and not something he used in response to Sasuke's attacks to counter them.Naruto used Rsm against Sasuke fireball jutsu and bijuu mode against his perfect Susanoo. I don't see how that's holding back.