The 4x7135 driver will work, but only drive the XM-L at 1.4A. I think Shiningbeam is using a similar driver in their XM-L S-mini. But if you want full power, you will want the 2.8A driver you ordered. Let KD know and they will send out the correct ones. But the drivers you got are great for XP-G's or if you want to drive a XM-L pretty conservatively.
Contact KD and arrange for a replacement. From what I hear they will take care of things. Unfortunately that stuff happens and takes forever to get straight due to shipping times but it's the price you pay if you want to save every dollar. If you're pressed for time grab just one from ShiningBeam until the KD order is straightened out.