Ok...i could be wrong but the H500 for example was designed as a work horse say for slinging etc:...so the pilot could sit on the left and lean out the door and have the collective in a comfortable position...have worked with senior pilots who use the duals say in a jetranger to sit on the left. The right hand thoery i agree with, easier to operate radios etc, may also be why the army version of the h500 the PIC sits on the right, obveousley for this reason, interesting topic,