So we sort of resolved the issue.
We created an IIS SMTP connector on a server and pointed Campaign Manger 10to it (this is our legacy spam mailer) and then had it send to our MEG 7cluster.
We noticed speeds go from about 300 emails every 10 min to 400 emails in 30sec.
Next I changed the setting on the IIS server to be what support recommended,1 email per connection, and saw the speed jump to about 7 seconds for the same400 emails.
So basically there is something about how Campaign manager sends email tothe MEG that it does not like and it really slows down the sending.