Your gaming experience will be better on QAM16, that said if you migrate to D3 network there is no guarantee that you won't tune to a over used upstream.
The D3 upstreams are in a worse state than the older network right now. Broadbandings will back me on this
As for downloading a large amount to be migrated over, errm no. That may have been the case a while ago, but not any more.
Who is this "Specialist", his first name would be handy if you know it.
AFAIK escalations are dealt with by 2nd line and you don't have to wait a week.