I don't know that it's quite that long, but minimum 700.
Another thought on Moffat and the themes he plays with: Matt Smith's run has, consistently, been haunted by the image of a reluctant warrior who will one day die a violent death. But the last two episodes have both used, at one point or another, the image of the Doctor living a peaceful, quiet, retired life. Granted, occasionally punctuated by [spoiler]fucking hellfire raining down from the assembled armies of every monster race the show has ever produced[/spoiler], but you know, you've got to keep the show exciting.
The thematic significance of Night of the Doctor and Day of the Doctor isn't exactly subtle; it's right there in their titles. The suggestion is that they're bookends, from the Doctor entering the Time War to the Doctor redeeming himself and rescuing his people. The darkness and the guilt are lifted, and his future is bright again. Not to say we won't see the Warrior Doctor persona again -- as I noted, the first time we saw Capaldi's face it was scowling -- but I think Moffat's really looking to shift the tone and the vibe here.
At least, insofar as we're looking at arcs at all. The show's been mostly episodic through his entire run, really, and that's generally been a pretty good thing. I think that's probably the thing people are cheesed-off about with this episode -- not only is it a regeneration episode, it's THE regeneration episode, resolving the limit; it's what Moffat's been building toward from day one and we get definitive answers on the cracks, who destroyed the TARDIS, the Silence falling when the question is asked -- all that stuff -- and ultimately it's all background noise in an episode that's another one of Moffat's quiet little fairy tales. Didn't see that coming. But the more I think about it, the more I like it.
ADDING: Smith also totally killed it playing [spoiler]an old man. It's not old age makeup that sells a performance like that -- no disrespect to the makeup artists, who also did excellent work -- it's the physicality. The stiff movements, the weakening voice.[/spoiler] I was very impressed, and I hope he goes on to some good roles from here.