Deploying only the CAS role for SMTP relay purposes

Hi Everyone,

I'm hoping others on this forum have some thoughts on whether it is worthwhile deploying only the Exchange 2013 CAS role for the purposes of SMTP relay.

When using Exchange Online, most guides suggest installing the IIS virtual SMTP component in an environment if SMTP relay is required. This is simple enough, however Microsofts future plans for IIS vSMTP look uncertain.

So my question is, has anyone deployed only the Exchange 2013 CAS role in an environment solely for the purposes of SMTP relay?
One pitfall I'm thinking about is the autodiscover service. Once the CAS role is installed an AD SCP is created, so this could cause potential problems.

I'm not concerned about having to extend the AD schema, or the cost. It's the other technical bits :)

cheers!