Personally, I think that the fact that Kyuubi has more limbs to his disposition would come very handy, as tails could be used to subdue PS movements. Lets not forget that they are very, very strong, since just one was able to hold another Bijuu in place, and Im talking about BM Naruto who had only half of Kyuubis strenght to his disposition. Also, PS slash cutting Kyuubi in half? I dont see it. It would trully mean that PS >> Kyuubi in overall power. Affect him to some degree, damage, but not cut in half.