I've been using synthetics for about 20 years since I could afford it out of college.
I change it every 6,000 +/- 1,000 miles. I've never had any problems, and have noticed positive things such as extremely clean oil pans or valve covers without any traces of sludge after 100K.
All professional race cars use it, if that's worth proof. Also, I believe R&T stated a BMW study that said that its good for over 10K before oil change.
Snake oil, definitely not; miracle cure, definitely not; the best lube you can buy with characteristics superior to crude based oils, definitely yes.
I think we have put the question of its great benefits to rest many years ago.
