We have many environments that are having issues with EDNS that have Server 2012 DNS servers - the roaming agent isn't working properly until we add the reg key noted here:

On future agent versions can the agent auto-detect this so that the reg key doesn't need to be added? I would think it's simple, as if a request turns up with rcode = SERVFAIL the agent should then try to send a standard DNS query instead of EDNS.