i'm left handed but use either side in composition. i think it has more to do with natural processing of visual information. if a subject is on the left, it may be more in the foreground and the background sort of follows it or is subservient to it. you know, reading left-to-right. if the subject is on the right, i would think the other areas/info in the image lead up to the subject. so i think the placement subtley defines the relationship between subject and other items/people/subjects in the image.