but then again, even the shiki fuujin seal of the death god{shinigami} cudnt truly confine the kyuubi, let alone send its soal to hell. so i really doubt inuyasha could either/ also, the attack reflection definately has limits, cause otherwise thered be no point for inuyasha to even bother about the sakon shards etc etc or naraku.
You mean the 4th Hokage's move? I don't think he was trying to send it to hell, just contain it. In fact, it seems to be implied that he specially sealed it inside Naruto for some unknown reason.
And yeah, Naraku's a walking plot-device, but so is Inu-Yasha as long as he carries that sword. It wouldn't surprise me in the slightest if he jdid manage to successfully take out the Kyuubi with his own demon energy or just sealed him away, especially if the fox is still inside Naruto.