Well, a 10 amp 100 watt panel would only put out 10 volts so that would be pretty useless for RV purposes. I suspect whoever told you that or wrote the story doesn't know much about the subject. Unfortunately, most reporters writing stories about solar seem to get totally confused by electrical specifications.
Efficiency in a solar panel is simply about size. The more efficient 100 watt panel will be physically smaller than a lesser efficient one. On an RV with limited roof space that does have merit.
I talk to lots of people who seem to confuse it with fuel efficiency in an automobile or something. When you're paying for the fuel efficiency is very important. When the fuel (sun light) is free who cares how much you use, if you have the room for the collectors that is.
