aristotle - 6:47 pm on Jul 14, 2013 (gmt 0)
1200 words isn't long at all. I would call it mid-length. I have a 6000 word article ranked no. 1 in Bing and no. 4 in google - it used to be no. 1 in google but the site was hit by penguin. I've seen Wikipedia articles that are 10,000 words or more ranking no. 1.
Do what's best for your readers. Personally I don't like to try to read an article that's broken up into short pieces so that you have to keep clicking to a new page.