I am planning my upgrade/migration from 2013 to 2015 and am wondering if I am able to do all the 'prep' work ahead of time (i.e. configure claims-based auth and IFD) and then all I have to do when I'm ready to flip the switch is just import the org and update the DNS to point to the new server.
I'm just a little unclear on how the ADFS server will treat more than one server.
If it's possible, I can see using this for failover too by having a warm 'standby' in the event of a failure.