I have some pretty extensive experiance testing Vorad systems on big trucks. I can tell you they have proven themselves to improving safety results. they are good systems, however...
For the same reasons they haven't really "Hit" in the commerical world, the won't "Hit" in the RV sector. The are simply too expensive, and most people are not willing to pay for a machine that does what they can and are supposed to do.
One thing I did find interesting with our testing of vorad systems. When we took one of our drivers who had the system installed for more than 90 days, and put him in another unit without the system, the likelyhood of that driver having an accident increased over 100%. Basically the driver became dependant on the system, and complacent in basic driving techniques.
Overall, I think they are good ideas, and they work well, but they are costly. Frankly I am still in the camp that they are really overkill.
"It's always wrong, everywhere, for anyone, to believe anything beyond insufficient evidence" -- William Kingdon Clifford
John (N9MXX) & Derek (KC9KEM)