I threw with this style for years when I was in Jr. High School - at that time I had a personal best of 180' - My coach taught me to keep the right in front of the left before the plant and as a result I carried more momentum into the plant versus in effect having a double plant (right and left) - At first my distance went down and I thought that this was the stupidest idea ever. I was a power thrower and didn't feel powerful any longer. After a few weeks my distances crept back up and eventually I surpassed the 200' barrier on to eventually throwing 71 meters. As a coach now I stress how important it is for the throwers to avoid the baseball crow-hop style, even though they give up a bit at first I know that once they become comfortable they will add distance and power.
I often progress the throwers through a "gallop" style similar to the baseball slide or shuffle to introduce the technique. This gets them away from the behind cross-over. Once they get comfortable with being at least neutral with the right leg, I'll get them bringing the right leg in front of the plant leg and voila they will start adapting the transfer of momentum to the plant and eventually adding distance. Good Luck -