About 15 or so years ago.. In my tool and die shop I helped a guy proto type a 3pt, cat 2, power opener over seeder.. The target buyer for this was to be golf courses and sports field operators..
I was told it worked great with higher germination rates than expected... I suspect this type over seeder would work well with many low till, no till areas.. I also suspect it would work well with many small grain seeds, but not sure how it would handle row crop type seeds, like corn or beans in the mix..
But then if you could get a small seed planter to do 80% of the variety you want to plant.. Then do the last 20% being big seeds with a corn planter....
When I plant "food plot" type plants for our small livestock, I disc or chain harrow, hand broadcast, and cover with the chain harrow or a brace of light truck tires to cover.. This being the cheap way, but adequate for our use..
My 5 cents of experience..