More cam usually means more overlap. This leaves exhaust gas in the chamber which is slower to ignite - adding some initial advance frequently helps. Since the intake valve closing is also frequently later, cylinder pressure is down - so the extra advance may not cause knocking (or at least less than you might expect).
Pay careful attention to the complex shapes of both the center rotor and inner surface of the advance weights shown. As engine speed increases, the spark increase is NEVER linear, but has periods where the speed (degrees per 100 rpm) changes. 2 different weight sets will give different characteristics even with the same curve. This is why a Sun machine and an experienced operator really help.
