Part 4 is the bestest Part, they'd have to be fucking crazy not to adapt it after they've done Parts 1, 2 and 3.
Whether they'll continue on after Part 4 is another question, since it's all downhill after that (though I hope they do if only for the sake of getting to Jolyne, who had better keep her Miyukichi voice).
I wouldn't say it's downhill, although I'm not a huge fan of 5. I like 6, 7, and 8 a lot though (although I haven't kept up on the latter in a while). But Part 4 is awesome, we can agree on that.
