A few months back, on a whim, I ground up some whole oat horse feed to throw on my no till bags. To my surprise, many of these seeds survived the grind and sprouted. After having light blocked out for like nine weeks, the oats are still alive and actually starting to blanket the entire surface now that there's no plant blocking the light anymore. They seem to grow faster and be more resilient than any of the covers I've planted in the past. No need to replant between runs. The oats will take over the empty space naturally once it can get enough light. Is there any reason anyone can think of NOT to use oats? So far, it seems like a stroke of good luck!
I assume that, because it's not a nitrogen fixer, that you mean when chopped and dropped? I've just been treating it like a lawn and chopping it down when it gets tall, lol.
I've heard about mixing grasses with legumes to balance N taken by grasses. No first hand experience tho.