I primarily use these gratings for my spectrometers (my professor supplies them for his optics class) as I find the square shape to be easy to build things around without messing with a dvd. Like the above comments say, you will lose a bit of resolution with the smaller angles, but you can adjust this with lenses or mirrors. These lines do not have the encoding the DVDs do so when you optically magnify the image in any way, they cause some distortion.
I have been working on a set of optics experiments at the university level for my thesis. I would love to hear about what you plan to do.