The United States has a history of late as not educating their citizens too well. Same goes for USTA. I guess keeping people ignorant helps idiots stay in power.
Anyhow, there's no such thing as Eastern Grip, Semi Western Grip, & Western Grip. There are some 6-7 grips one can use on a forehand. Federer, for example, has his top part of the hand on number 3 bevel, and the bottom part between bevel's 4&5. Sampras was completely on bevel 3. Their forehands were very different, but most people around here say they both use Eastern Grip.
The swing also effects a lot as well. People develop different swings, preparations, and finishes which can do different things, irregardless of the grip. This also must be discussed as one, as opposed to being so general stating " Is the Semi Western Grip the Best ? "
Lastly, it may be better for Tomas Berdych, but not for John McEnroe. Your physical characteristics play a part in this...
Nadal, Djokovic, & even Roddick are all on the extreme side of the Western Grip...
Let me know and I will email you an article going into detail regarding forehand grips, and the many grips, preparations, and finishes associated...