I went back to the Surge Guard website and looked again at the specs on the various models. Below is a summary of what I found:
ALL of their 30 amp models except the 44740 surge-only will cut off the power to the RV in case of open neutral or high/low voltage.
NONE of their 30 amp models will cut of power to the RV in case of reverse polarity or miswired pedestal. They only give an indication that the problem exists.
ALL of the 50 amp models cut off power to the RV in case of open neutral, high/low voltage, and reverse polarity.
The 40240 50 amp hardwired PLUS model is the ONLY model that gives line frequency protection. This model is very similar to the Progressive Industries HW-50C except for the response time and warranty.
They all have a 1-year warranty with no after-hours tech support.
Now compare the above to the Progressive Industries units.
ALL of them, 30 and 50 amp models, cut off power to the RV in case of ANY of the faults mentioned above, including the line frequency.
All models have a lifetime warranty with 24/7 emergency tech support!
These are the facts as best I can tell. If I have misstated anything I would appreciate you calling my attention to it.
Hopefully this will clear up some of the confusion.
Good luck, happy trails, and God bless!