Couple issues with this. First is there's no room on the left if you put B for every business. I have so many signature required, sureposts, call tags, etc, that all I'd ever see on the left is *. Second, the DIAD pretty much knows all the commercial stops already. Go to a commercial stop and try to DR 'front door' instead of CIR and watch it beep at you and go back to DR main screen.
I think having commercial and residential stops separated in the DIAD for the driver to know would be a good idea. Maybe with the next gen DIAD they'd have more room on the screen to indicate it. And perhaps if they could build this information into ORION that'd be beneficial too. I find I often have a random business or apartment office scheduled after my pickups, which end at 1700.