I did the ARR and HW EX's synced, they were nice. But from SB onward, they seemed to change, the mechanics just became more and more punishing. I don't know, maybe the ARR and HW ones were more punishing on release, and because I came in late and had the benefit of the Allagan tomestones gear, they were easier?
It took around 1 - 2 hours to complete each of them.
I jumped back in recently with the Zoraal Ja EX with some friends, we put up a PF for an extra two people, and it just wasn't any fun. I wasn't coordinated enough for that silly stack moving mechanic. We tried for an hour, and even though the PF said blind and practice, we still had people jumping in and out constantly, after the second or third wipe.
Edit: I also really enjoyed doing the blue mage challenges for the titles and the rewards (the umbrella)
That kind of content seems to be the perfect difficulty for me.
It's not fun to me. All respect to those of you who enjoy it, play it to your heart's content, but I much prefer the slow solo deep dungeons challenge. I don't have to wait for other people, I don't have to watch them get frustrated and leave, I don't have to feel bad about my mistakes and I can just go again and learn at my own pace.