Dont know about that type of sharpener, I have a Gatco kit. Anyway inside the box they got an angle guide chart. I'd imagine opinions on sharpening angles vary, but heres what it says:
* = degrees
11* Most narrow bevel; produces razor sharp edges. For Xacto blades, razor blades. Requires frequent re-sharpening.
15* Superior sharpness for woodcarving instruments and thin specialty blades.
19* Fine edge excellent for fillet and boning knives.
22* Ideal for kitchen cutlery and other high quality knives.
25* Wider bevel; more durable edge. Perfect for pocket, folding, hunting and fixed blades.
29* Widest bevel, lingest lasting edge. For utility cutlery, carpet, linoleum, electricians and serrated blades.
I'd say based on this chart use your 20*, especially if thats the factory angle. I believe it may be a bit sharper than the 30*, even if you have to re-sharpen it more often.
If anyone finds fault in this chart or my reasoning, please feel free to correct me. Always open to feedback.
Hope this helps Cipo