Maybe my head is in a different atmosphere or something, but in all my life, I've never had any problems with any kind of electric space heater, except once or twice. Maybe it's because I use some common sense when operating them.
Over time, and because of marketing, the old style red-hot wire heaters were replaced with the more modern ceramic, square box, style heaters, or fan blown heaters, or the oil-filled heaters. The bottom line is, what's being manufactured today is simply much, much more safe than what was manufactured 30 or 40 years ago. Used with some sensibility, and all of them should work without issue.
I have experienced failure in the oil filled radiator style heaters twice. In both situations, the heating element would not shut off. The thing just kept heating and heating and heating. What was the result? The heater itself was OK, but the electric wire running to it was extremely hot!
After two bad experiences with the oil-filled ones, I quit using them all together. Fortunately, I was right there when I realized something was wrong.
So, now migrated to the little square ceramic style heaters. Never had an issue with any of them.
I think it's more important where the portable heaters are placed, more than the brand or style you get. We have 3 places we position the heaters. The first is on top of the stove. After all, that location is designed for heat, and it's high enough and in sight enough, nothing should ever bump or tip it.
The second location is on a counter top. Never on the floor. Again, it's high enough it's in sight all the time, no threat of tipping, and in the open. Just make sure nothing is placed in front of them, or right beside them.
The third location is the bathroom shower with the door open. Yea, bathrooms get pretty cold!
I think, all the contemporary models and brands and styles are good. Mechanically, there is only so much heat electricity can produce regardless of the new-fangled claims. The difference is how the heat is disbursed from the source... fan or radiant.
So, in my opinion, go to Wall Mart, find one that fits your price range and one that is appropriate for the size it will be used in, be smart in where you place it in your RV, and just enjoy.