Avrus is a Whiskey regular, and I did warn about relying on them. Avrus might be a reasonable exception to this rule. He and Stonebelly are real life friends up there in Kanuckistan, and I think he wants to go to your raid so that he can spend time with his buddy. I rather expect that he'll get bored of doing ToCx2 on Avrus, and will want to swap out his warrior at some point. If that happens, expect Avrus to have his warrior totally geared up before asking to swap without outside pressure. You'd be trading your top DPS for more raid buffs (sunders, commanding shout) while retaining an interrupter and your melee/ranged ratio, so it would probably work out just fine.
If you accept him, you might want to pre-empt him about the rogue/warrior thing and either debunk my theory or establish a time for the alt swap.