I personally have never used a diastatic malt extract, but from my understanding, they are just made to have higher diastatic power. If you not familiar with all grain, the diastatic power of grains is its ability to convert the starches of itself and other grain into sugar. The only reason I can see you need the diastatic extract is because there would be a lot of specialty grains in the recipe that need to be converted. However, you usually dont steep the grains with the extract so that wouldnt make a difference.
Any chance you can post the recipe?
Primary1: Pumpkin Ale
Primary2: Christmas Ale
Secondary: Sour Brown
Drinking: Warrior Pale Ale, Wit, American Rye