If you search the forums, you will see incidents of reverse polarity and other issues not covered by the less expensive unit. Also most surge protection components are single use sacrificial devices. If the inexpensive units blocks a surge after the one year warranty, you buy a new one. The PGI is replaced for the life of the unit. Easily worth the extra expense to me, but it is your RV and your choice.
2015 Freedom Express 248RBS
TV 2015 Silverado HD2500 Duramax
TST Tire Monitors
Honda 2000I + Companion
2 65W solar panels