I have done both, bradford/susquehana county line, Buckwheat early, grind it in & planted brassica's & buck forage oats together, It did fair, but then again fair is the best I have had here! It was all eaten.
I plant it oats often, the deer keep it mowed but not till cold weathet.
It's more of an energy food any way, but in the summer it matures and make great bird habitat. And if you just till it under it will give you a free crop.