The beauty of the KME is that it keeps a very consistent angle.That's a big deal for the sharpening challenged.A second big plus is that it is adjustable for angle to match any blade.Once that bevel is trued up and fitting the flat stone,any subsequent touch ups or sharpening take little time an remove a minimum of steel.That is due to the angle being repeatable.
The OP's problem is that the Delta's edge isn't dead straight,so doesn't contact a flat stone,full length.When the Delta came out,most broadheads were built that way,none were hunt ready and most used files to sharpen them so didn't care if the edges were straight or slightly concave.
If a person takes the time to get the Delta's edge fitting the flat stone,it can be sharpened very easily on the KME,and all touch ups will be a breeze.
Again,it is well worth your time to call Ron if you have any questions.I personally have never had broadheads so sharp since learning to use the KME's.Good luck.