Although both are 'Grasses' Their root systems are different. I believe a blend with a max of 20-30lbs each gives a lot of advantages. Then add a couple of broadleafs-your choosing. Turnips, radishes, vetch, etc.

I find either easy to kill-before they get too big. But recently I have been delaying killing until the corn is emerged 3-5 inches.The more mature plant is again easy to kill. At that time the rye is tractor tall.

Every one has a different preference.