Joel,
That is a very good point and well taken. I was trying to be clear that this unit does not cover all the bases that the Surge Guard unit does but I did neglect to cover all the possible electrical issues one could run into that the other devices cover.
The two issues that seem like the most prevalent risks, based on my experience, are a low voltage condition (mostly on non 50amp service) and spikes from lightning strikes hitting the grid somewhere or spikes induced in the grid by electrical motor inductive kickback.
We live in lightning territory here in coastal Alabama and when home our coach is always plugged in. If I'm at home I will typically unplug the coach before a lightning storm and will continue to do so but you are not always available or awake when one occurs. For me the risk of a stray spike on a powerline was high and so that was my main reasoning for this minimal investment.
Even if you have a Surgeguard installed this Eaton unit would be extra insurance. The joule rating is better on the Eaton device and the amp rating on the Surgeguard is 6500amps vs the Eaton is rated for 120,000amps both having a conduction rise time of less than a nanosecond. That just means that the Eaton can instantaneously pass a higher short duration current much better than the Surgeguard can. These devices can work together, having both online in your coach would not be a bad thing....
Later Ed