While i'm not a huge fan of his, Clapton sets are welcomed here. Anyone who doesn't think so is just plain ignorant about music and the influence he's had over all genres of rock/metal. If you doubt this check out some stuff from when he was in Cream during the 60s. They were writting heavier blues inspirered rock before most bands, including Sabbath. In fact Tony Iommi has credited Eric Clapton's guitar sound with Cream as a major influence on him. In "N.I.B." Iommi uses a riff that sounds simular to Cream's "In The Sunshine Of Your Love"
So to sum this up:
No Eric Clapton = No Tony Iommi = no metal.