It's hard to hand pull. The stems break easily. When you mow it, the pieces spread by the mower tend to reroot.
Also, I have found that the 2, 4-D sold to the farmers is a lot more potent that the stuff sold to homeowners.
Your correct on the 2-4-d it is a slightly different formulation than the big box stores sell. If you can go to your local coop or Agronomy location....Roundup is the same way. the stuff you buy at hoe depot , or walmart is weaker than the stuff at the local coop.