is a great way to start, but my concern for this is the impact of when your Toon1 [ie your main] gets crowd controlled. I know for a fact that polymorph completely screws up the targeting of my alts when i use the focus main method, and I have to switch main's (via focus change) on the fly. Sap is less of a problem because I can still control the alts via the main's window when he's sapped. Sap doesn't seem to screw up the targeting like poly does. I've had mixed results with fear in PVE (and i swear in pvp but pvp is more chaotic so i'm not positive.) Sometimes after getting feared my alts won't attack what my main (using the focus method) has targeted until I retarget. It's really a PITA but it happens so rarely i'm not sure what the cause is, however it seems to happen after fear.
Have you tried using sticky targeting? Atleast if not hooked on with me it used to change targets during poly and fears..