They would sound sweet with a blast part over a heavy riff.Even a lasting thrash beat.They do some fast stuff, but nothing like Slayer or even Morbid Angel in the fast department.I guess that's what keeps them interesting eh?The only thing "fast" about Opeth is the double bass parts.Which is just fine in my novel."AprilEtheral" is the shit and ""wREATH" is killer also!