just like it was said before, Itachi was already tired from a huge and exhausting battle, maybe that's what it made him colapse, plus he is using A GOD, of course it doens't suck and of course it takes lots of risks. Remeber that warrior who fight a nine tails fox demon, Yondaime Hokage, he also used A GOD and ended up dying. Itachi is doing the samething. Invencible and then... Welcome to Valhalla.
The move was nearly comparable to Minato's Shinigami summon. Its sealing is seemingly less permanent, I'd expect both are inescapable in most circumstances but the shinigami's stomach seems more permanent than a bottle even if they are both practically eternal, but it gives you better defense. So the price will probably be comparable as well.