I don't think it is a big deal. Someome once asked about using outlines about 10 years old(?) and I wouldn't use those. But 1-2 years won't make much of a difference. The only thing you would be missing are some of the more recent cases that might be important (like the Poletown case in Property, etc.), but if it is that important, your teacher should cover it in class. I use them as a guide for structure for my own outline and to give a better understanding of a specific issue so an outline that was published just 1-2 years ago shouldn't make that much of a difference.