I agree with the comments above. I ran a +6+5 CB for two years/30K + and "high speeds" and now run a +5+4, both with reverse contour. no issues at all, other than the fact I believe it does cost me some mpg. I do check the screws on occasion just to make certain and have never found them to be loose or had any other hardware issues. Now I am at 55K. I find that I ride with the screen in a lower position than I used to and could actually use a +4+4. When around big trucks I do drop the screen to the lowest position to reduce the buffeting on the screen.
BTW - I still have the +6+5 w/reverse flip if anyone is interested. Drop me a PM and we'll work out a price.