My employer has been using Connect via annual contract with one of Adobe's resellers. Now, they've decided to go enterprise. As the main in-house tech guy, what should I expect from the transition? Will there be any differences in performance visible to presenters or attendees? How about behind the scenes? Will I have more control than before and, if so, of what? How will this affect our network? Is there a primer somewhere that helps explain the differences?
Not sure that there is a primer or any real guide for the transition. Here are my thoughts though.
All current Content, Meetings, etc. will be lost. The two accounts won't merge, so if anyone wants the same content/meetings then that may be part of your job on account set up to re-create the rooms or re-upload the content objects to the desired folders with the desired URLs. That is no small task, so usually this kind of transition comes with the caviate that it will be a fresh, new account and everyone gets to start over.
Performance is generally improved with an on-premise account, but this is wholely tied to the performance of your server(s) and the bandwidth available. If users are on the same network as the server(s) then there can be almost 0 latency and uploading objects to the server can be lightning fast. Other than that, I'm not sure there will be any visible difference to the Presenter or Attendees. Well, unless you don't do version updates, and then some may notice features that are or aren't available, but I feel that is fishing for an answer to your question.
Behind the scenes you'll have full controll over this deployment including access to the SQL DB. Usually Connect is a pretty hands off application but you can do things like LDAP integration, Single Sign On, custom reports and monitoring that isn't available with a hosted account. Other than that, there isn't much exciting about back end management. Well, you can shut down the servers and make work for yourself (job security!). What do you want/need control of? Was this transition done because of a specific need?
As to your network, it will cause more traffic on it, because everyone connecting to Connect will have to come to your server and then also recieve information from your server. So, be ready for that additional traffic. If everyone is on your internal network, then it may not be as big of a deal, as everyone was causing that traffic before, but they had to go to the public internet with the hosted account.
As a way to guestimate some numbers of bandwidth consumption, I'd recomend you play with the bandwidth estimates on the next to last page of this document: https://dl.dropboxusercontent.com/u/19289500/Adobe-Connect-9-Technical-Guide.pdf