Something to be aware of is how Symposium routing will affect Genesys.
If you are running with places and place groups, then Campaign Manager will see agents login by the turrets appearing in a particular acd queue which corresponds to the required campaign. It will then dial, for progressive, based on agents going ready. However, there is no link between these agents being ready as far as Genesys is concerned, and whether they are in the skill group for the CDN which you are going to deliver the call into.
There is therefore a bit of a management overhead running Genesys under Symposium as opposed to CCR.