The better surge protection devices also provide protection from HI/LO voltage conditions as well as issues with the neutral and ground (ie: reverse polarity and open neutral). These are the most common problems that you will encounter with a campground power source and are conditions that will destroy electrical components pretty rapidly. I have experienced power issues several times in the 11 years we have been RVing (the campgrounds in the northeast are pretty dated) so I believe they are worth every penny.
Lou
05 Travel Supreme Envoy