The 30K oil change interval isn't hype, wether people are comfortable going that distance is a different story. People who purchase Amsoil do it not only for the protection but for the convinence of not having to change their oil 4 to 5 times a year, assuming 15-20K miles driven. If it were all hype then all the user testimonials must be wrong and the people using the oil to 25K or 30K clearly destroyed their engines, lied about it and then promoted the product that ruined their drivetrains. Seems a little far fetched.
Like I stated Red Line, Royal Purple, and Mobile are close equivlents(sp) and most likely are adequate if following their recommended guidance. Prices vary accordingly, looking at the Amsoil website lists the 7.5K drain oil retail at $7.45 to $11.10 for the 0W-30 which will go to 30K.
The only way to really "test" your oil is through oil analysis. We routinely did this with aviation piston engines. The results of the analysis showed
Amsoil routinely outperformed the standard Aeroshell products (dino oil). I can't think of a more demanding operating environment. Air cooled horizontally opposed engines, ranging from 235ci to 550ci, operating at maximum rpm setting for hours at a time. Imagine taking your Taco engine and leaving it at redline for 3 hours.
Folks will have their biases, that's why there are forums.