Front rows of seed were buried to deep and back rows would not be covered. Plugging was more of a problem. Switching to narrow teeth has vastly improved our seed placement. If the fertilizer was on I think you could go to a 4 inch tooth, disturb less soil, and still have the rows close enough. We find we have much more flexibility on seeding date.
Moisture is retained near the surface longer.
We find we are seeding shallower into firm moist seedbed when we want to. Variety selection will depend on weed spectrum and seeding date. Westar is higher yielding if seeded early. Tribute or Triton are triazine tolerant and can be sprayed for wide range of broadleaf weeds. Tobin is early maturing and fits well in zero till if you are delaying seeding due to weather or waiting on quackgrass.