I selected Coach-Net over Good Sam after reading all the positive posts in Rec.outdoors.rv-travel (or whatever it is). Good Sam Roadside Assistance got mixed reviews. Some bad reviews could be written off with the stupid-owner category. The big issue with Good Sam seemed to be long hold times. I don't want to be on my cell phone for that long. Coach-Net answered quickly just as advertised.
I have only used it once but was pleased. My understanding is that the phone staff is trained in RV's and they also have a more advanced technical staff to assist you. I was happy with the one time I called them. They did give me some advice and explained my problem in more depth. They have on record my RV model and year and gave me a quick training session.
For $99 a year, it's cheap compared to a tow or roadside assistance on a 345 MH! Not having it would be penny-wise and pound-foolish.