AFAIK, your account needs to be "flagged" as a real-time network account. During beta testing Airnav activated it on my account to enable beta-testing, so I'm guessing that:
1. By default, you'll still be on the delayed network.
2. If you pay the real-time subscription, then you'll get the real-time network.
And yes, it's as real-time as possible. It gets data from the Airnav server every 20 seconds, and their server gets real-time data from Radarboxes on the network. So the display could be around 20-25 seconds behind real-life.
In testing, I found the Airnav real-time network was more up-to-date than another flight sharing network, which I used for comparison. The transition from hardware to network flights works very well, but you may need to reduce your hardware timeouts to get the best from the real-time network.
Some example transition videos on my Youtube at:
http://www.youtube.com/watch?v=pEJOHvQ4Bbwhttp://www.youtube.com/watch?v=NiiLcJhjaOA