Stofen omni-bounce - best angle?

With the stofen how do you shoot it to get the best lighting? Straight up or at an angle? Or is it just a guess and test game for each secnario? Also, do you need to go fully manual due to the flash output being lowered so much or can you use some of the semi-automatic modes?

When I use one at all, I just aim it up. Make sure you have a white ceiling and walls or its useless. ETTL works fine.

There is virtually no effect on directionality or intensity of the light from the flash, when the Stoffen is on the flash head at one angle vs. another, either for light going up to the ceiling and bouncing or light going straight forward to be seen as catchlight in the subject's eyes. The size of the catchlight can be increased a tiny amount (1.4x) if the flash head is aimed upward at 45 degrees, as that provides a larger apparent size of the source as seen by the subject.