Changing Domain controllers with Direct Access Deployed

Hi there

I am about to de-commission an oversized SBS network, replacing the SBS 2011 machine with a Server 2012 R2 DC. As there are remote clients, I would prefer to install DirectAccess (on a 2012 member server)  first to make it easier for them to connect and update GPO's etc. I understand there may be complications with DirectAccess and changing Domain controllers like this.
Can you shed any light on this scenario? Is there any reason I should upgrade the network first or will DirectAccess continue to operate fine as long as I update DNS?

MIS5000