what kind of  conditions?   Sand, clay, irrigated, dryland?

With  my 7.5's    seed spacing is  further apart in the row,  and   if it weren't for  irrigation,  some of those  seeds may not be able to punch through on some of my  more heavy soils after a heavy rain.

If you are in  a  higher  rainfall area  on  heavy soils,  then the  7.5's/ white mold thing  kicks in  

I like the  much quicker  canopy  with the  7.5's.  Even with irrigation,  conservation of water is dollars left in my pocket  and   weed escapes  have been basically zero  since  going to  7.5's.
  I don't  pre emerge spray.   I see what's coming for   volunteer corn, and   accordingly spray once.   Done and done.  
Make sure you  pick varieties that do well in drilled conditions.  Semi to full upright varieties.