O assistente de backup no console do SBS usa o utilitário nativo do Windows Server Backup. Então você precisa de outro servidor, mas não precisa ser o SBS 2011.
De um artigo de technet Apresentando o Assistente de Backup do Small Business Server 2011 :
SBS 2011, just like SBS 2008, includes a backup wizard that is integrated into the SBS console for the purpose of allowing administrators to quickly create a robust backup/restore strategy without requiring them to have prior experience in Windows backup technology. It’s a simple custom interface that calls upon the native Windows Server Backup utility to do its work while keeping much of the underlying complexity in the background.