One of the local auto-xers, who is a National Solo Championship contender according to the SCCA's Sportscar magazine, has been using the Dominator 10W-30 oil in his DSP BMW for several years now. During a conversation last week about the advantages/disadvantages of various oils in the BMW M3 engine, he flatly stated he wouldn't use anything other than the Dominator oil in his car. (The M3 engine is notorious for camshaft wear and loose clearances.)
I found this to be a strong endorsement as RedLine Oil offers very strong monetary incentives to National Solo Winners while AMSOIL does not. He could swap out the Dominator oil, put in the RedLine, apply a sticker, and register with RedLine Oil and pickup a considerable amount of cash if he wins. The fact that he values the oil's lubrication and protection properties more than the contingency cash tells me he's convinced that the extra cost is worth it.
Just my opinion, YMMV.