Keep forgetting to take pictures, but since HP keeps asking how Arisaig is going, here's an update. It has a back, a right front and half an arm. The arm as written was going to be huge (I think other people have had this problem with the larger sizes too), so I narrowed it, starting with 56 stitches and increasing gradually to 96 just before the armhole cast-off rows. I think it'll work. And it looks like the yarn I've got will hold out too. Hoorah!
If you want to see a rather more nearly finished Arisaig, Princess Pumpkin is seaming one.
updated: I just discovered this blog is the top google result for 'Arisaig finished'. Shame it isn't yet.