Many Player don't realize SCH gets a bonus for certain subs. So far confirmed are bonuses for BLM sub and WHM sub. With WHM sub, SCH has higher def and magic def, allowing them to better survive stealing hate. With BLM sub, SCH gets an additional bonus to black magic when in Dark Arts. this bonus appears to significantly increase both MACC and MATT. It should be noted that this is in addition to the MAB that /BLM gives to any job. This information was released at the Osaka Altana Festival and appears on the official Japanese FFXI website.
I haven't seen this mentioned anywhere else, though honestly I haven't searched too incredibly hard yet. Can anyone confirm or deny the above statement?
I am playing SCH as a DD during the lower levels in a duo. If not for this bonus I think I would switch to /WHM eventually for Stoneskin, but not if the sub would make a larger hit to my MACC and MATT than usual.