Chopping? What chopping load can you inflict with a 4.3 inch blade? Maybe if 1095 is brittle, but 10° per side should easily survive chopping from a 9" inch blade, and I went down below that on some of mine with no troubles, even putting some side loads sometimes... I consider 15° borderline for a 9", so 15° is almost silly on such a small slicer: 10° per side is plenty enough...
The 20° per side standard is just ridiculous on such a small knife. Fortunately most Beckers, even the BK-9, ignore the standard, and are around 15°-17° from the factory...
Gaston