Well, maybe return to the actual discussion of re-reading Impel Down.
I got to say, yes! re-reading it is definetely a much more eerie exsperience than it was reading it the first time around.
And here's why, at least in my opinion.
The first time the arch was being made and we read it, there was this clear sense of purpose and of hope, it seemed like such an "Of course." thing, that by the end of the day, Luffy would safe Ace, it would all be good, and it would all lead to this happy out-come, that was we all believed.
Which is exactly what made Ace's death such a sucker punch to the stomach, no-body saw it coming.
Now we do know, that is how it's going to end, Ace is going to die, no matter what Luffy does.
Which means, re-reading the arch, now we know, that all this crap Luffy goes through, all this fighting, all this near death, even going to Impel in the first place... it'll all be for nothing.. worthless.. Luffy will be going on this extremely tough path, and wont reach his goal at all, we all know the heart-breaking out-come of it. Ace will still be dead.
Now of course, in retro-spect it wasn't all for nothing, Jinbei was freed so he could join up with the ST's later and help them, as well as sort out his own buisness, Buggy got to make his out-law cast.. what-ever role those guys are going to have later, Ivan was freed and returned to the revoltuinary army, Luffys action here set off a ton of events that will matter in the future.. but these events were unforseen side-affects not even intended to happen.. the one thing Luffy is after, the one thing actually mattering to him.. is a compleately failed cause, no matter how hard he fights, no matter what he goes through.
And that's a very eerie feeling when you go through such a tough long arch, knowing that all of this crap, will ultimately be for nothing
To top that off, he is alone and isolated away from his crew and the people he would usually depend on.. yeah he finds BonBon, Jinbei, Buggy and Mr 3 but...
In his last sould crushing hour as Ace dies... Luffy is alone.. there is no one there of the people he came to trust, to put a hand on his shoulder, no one.. he is alone.
And it actually becomes Jinbeis job, a complete stranger, to beat semse sense into him at last, and then comfort him.