As long as you allow people to play with more than one alt, alts give a boost in domination anyway. You can push forums, interrupt, and help out klanmates in other brackets, which ultimately helps you. If you have only one character, you’re at a pretty big disadvantage before you even take raiding into account. All keeping alts out of raids will really do is limit who can realistically raid and give you a false sense of security that alts aren’t an advantage.