The field in the pic is actually wheat and it was killed within 24 hrs of planting.  I have only tried it for two years but so far I am pleasesd with the results.  I can tell you better in a couple weeks when I harvest the corn!  I like the massive amount of residue for when the heavy rain comes right after planting and also the mulch when it gets hot and dry. If you were to look at the field in the picture now you would have trouble finding any remaining wheat,I wish I had more.
     I do think maybe I give up a little early growth, but I think I more than regain it later in the season. It's kind of hard to tell because visually the corn just looks kinda ugly when it's coming up through the dead wheat.  The corn is a foot tall and you still can't see it looking across the field.  I'm not sure if the corn really is hindered or if it just appears that way because of the contrast agains the tall dead cover as opposed to traditional brown soil.  I am playing with some ideas of how I could flatten the cover as I plant.
     Another consideration to keep in mind.....if soil conditions are dry I don't think you would want to let a small grain grow to the size of whats in the picture due to the fact that small grain that size can pull moisture in a hurry.