I have Good Sams ERS and have only had to use it one time. On the way back home from spending the winter in Florida a few years ago, I accidentally put a whole tank of gasoline into my diesel truck. I realized it when I looked at my receipt after paying.
Called GS and they sent a truck to take me about 40 miles away to drain the tank and purge the lines. They also offered to tow my trailer to a campground or other safe place but the Flying J said I could leave it there.
The tow truck arrived within 1/2 hour of my initial call, and GS operator called back twice to make sure I was being taken care of. I did not have to pay a cent nor did I even have to sign anything. About 5 hours later, we were on the road again.
In my opinion, they did a great job and I could not have been more pleased with the service. I would not travel without some kind of ERS for both the truck and RV.
Barney