Sharpening SlickTricks

First this is NOT a ST bashing thread. I love them and have had no problems with the sharpness out of the box. I know they are working on the blades and using a German company to make sharper blades for the new versions and can't wait until I can order some of them. I have 2 remaining STs and no replacement blades. Instead of waiting on the new ones to come in I need to sharpen these (been through animals and in my block target) for a hog hunt. I was thinking of using the 20 degree angle on them. What angle would you use? 15, 20, 25, or 30?