JMO but I suspect 9 out of 10 - or perhaps even 99 out of 100 :E - who buy a simple surge protector such as that mentioned by the OP buy it for the wrong reason - price. :( These simple surge protectors do exist for a reason, bobndot being one of few who does have a legitimate use - to surge protect his expensive Hughes Autoformer voltage regulator, a case in which one obviously can't use an EMS with low voltage shutdown before the VR.
While surge protection is better than no protection at all I likewise suspect most who own a simple surge protector are using it incorrectly. In an earlier post DutchmenSport said -
"I've been using one like that for over 3 years now. My camper is plugged in 24x7x365 as we are able to park it at home. I put it inside the cabinet where the trailer cord shoves into, shorted the cord and put on a new female end. I then plugged the protector in there and shove the protector female end out the hole. I then use another 30 amp extension cord outside the camper to plug into.
I have this set-up for over 3 years now. Plug in and forget. Either it's working real well, or it's not working at all, because we've never had problems with anything funky happening with our power."
In reality lots of "funky" things have been happening with his input power - he's just not aware of it because his surge protector doesn't have the ability to do anything about it. If in fact he's leaving this surge protector permanently plugged in then he's using it incorrectly, just as I suspect most who own a unit like this also use theirs incorrectly. Since this unit can only monitor for various line errors but has no ability to do anything about it one should always plug it into shore power without the trailer plugged into it. That way, if a line source error is detected and displayed by virtue of a combination of lights on the front panel the owner will avoid passing that error on to the trailer. If one simply leaves the trailer permanently plugged into the surge protector then whatever error it detects will be passed instantly on to the trailer since it has no ability to disconnect power to it's output whenever an error is detected.
The bottom line is you get what you pay for. These simple surge protectors only monitor for error but have no ability to do anything about it - for that you want a full feature EMS.