Nick Smith,
You are right!! I my self am an Electrical Engineer, and practice this field now on my job. You can easily have a 120V motor that is more effecient than a 220V motor. It is all in how it is built. If you have a large IR loss in a 220 volt motor and have a very littel IR loss in a 110 volt motor then the 110 volt motor will be more effecient.
Also, I don't care how you look at it, the inheriat risk of 220 is for more dangrous than 110.....if thoes two hots get exposed then you will have big problems..
