I purchased a Progressive Industries 50 amp portable unit in 2015 after my Surge Guard died. The unit right out of the box didn't work right. The company sent me a new one and I returned the old unit. By the end of the summer, that unit wasn't working right. That unit failed during the 2016 summer trip. The same thing was true with 2017 and now this year. Thus, I have been through 4 units in 4 summers and am about to start on my 5th. If this keeps up, I may have to go back to a Surge Guard.
Before everyone starts jumping on me, the electric in my rig is fine. I had my RV repair person check that out. The places we have stayed at this summer have all had good, modern electric posts. I do think that having a unit is good insurance, would just like to have one that I can depend upon.