The upgrades to Branch Manager income don't seem to work.
Edit: After purchasing Sapping Technique, it's possible to get the Ichor boost with any job. Selecting Mind Control and then selecting any other job will cause Ichor to continue growing as if you were still doing Mind Control.
Edit 2: Leveling up causes Branch Manager to display as Schmooze at Ratcorp Gala, but it retains Branch Manager's effects.