I was alive, well, and paying attention (very close attention) to blues and blues-rock at the time, and this is the first I've heard of Jeff Beck joining Eric and Duane on "Layla." Duane's slide-guitar "voice" is pretty obviously evident on most of the tracks.

I find it hard to give credence to a claim that any serious blues player could be a "racist," although I suppose a person could respect and befriend artists like BB King and John Lee Hooker while still having a low opinion of non-musician "everyday people" of the non-white persuasion. But I find it pretty laughable that "racism" would somehow explain a Brit's supposed distaste for any White Anglo-Saxon Protestant American ~ especially a Southern boy like Duane Allman!