Well, the one on Kakuzu wasn't exactly complete (wasn't in Sage Mode, wasn't thrown)... the Pain body that got hit wasn't just cut in half, the lower half of it's body was basically disintegrated. And that was because it wasn't caught by the main attack, but only by the spinning blades after they extended (the Pain was caught by surprise). So if it hit someone head-on, with Sage/Kyuubi Mode level power, it's likely the person's entire body would be wiped out.
Originally Posted by shogun313
We also haven't seen the bodies run out of chakra. They're dead, so they probably don't generate their own.. their power either comes from the user (which would be a huge limiting factor!) or the the corpses' original strength (reducing Nagato's chakra to that of a fodder nin).
Or maybe they have their full powers intact, and just have to be one-shot. I'm sure will see all sorts of creative ways to kill them (Amaterasu, swarms of bugs, crushing them with sand, smothering them with lava, warping them with Kamui, etc...). I mean, we only saw them hit by exploding tags and the Death God. The Death God is incredibly powerful, and exploding tags never kill anyone. I mean, they didn't kill baby Naruto when they were hidden under his blanket. They didn't kill young Gaara, even though his assistant hid the tags under his shirt. They AGAIN didn't kill tailed form Gaara, and there was an exploding tag up his ass. They didn't kill Madara, and there were SIX HUNDRED BILLION of them. They didn't kill Nagato, and there were like ten of them on his legs and up around his thighs.
So yeah, surviving against those tags might not be the best proof of invincibility.