Over the years I had a slide-in camper, Class C, Class A gasser and now a DP. We didn't install a surge protector until we bought the DP. It's a matter of how much electronic equipment you have. My slide-in camper had a portable TV, the CLass C had a cheapie 19" TV and really nothing else. Even my gasser didn't have that much in the way of electronics. My DP is a different story. It has an inverter, Home Theater, 2 A/C's, two TV's, satellite and a few other things that need protection.
My opinion is it's like insurance as another poster stated. If I have a $500.00 car I have liability only. If I have a new Lexus, I carry full coverage.
With that said, I have the SurgeGuard hard wired unit. It has worked well and shut the power down on a couple of occasions where the voltage dropped too low. The first time I used it, it told me my home wiring was wrong. If I were to buy one today, I would buy the Progressive unit because it has more bells and whistles.
I believe camping should be easy, so mine is hard wired. I think everything you add to setting up camp just takes away from your camping time and enjoyment. If you buy the portable unit, you not only have to connect it, but you have to worry about locking it.