I don't think I understood what you mean there.  How does notill vs conventional make any difference in post weed control, or are you failing to get the pigweed killed in the burndown?  The only time I have had trouble with burndown has been a couple years where, lured by the new lower price of glyphosate, I failed to include the appropriate amount of 2,4-D. 

On the post scene, I have gone back to a 1/2 to 1oz kicker of 2,4-DB with all post braodleaf products and it isn't hard to remember why it was a good idea.  It sure does make everything work a lot better.   I used it with syncrony but got away from it when I started spiking with Blazer or Cobra because I thought it was no longer needed with them in the mix.  Well, they work a lot better with it.