In MyFlights, I can track aircraft arriving/departing my main local airport (Manchester) above about 2000ft. With the 5 minute delay, I was seeing departing aircraft on MyFlights before tey would appear on the network, and I'd have to wait 5 minutes before landing aircraft would actually "land" on my screen.
With the live network, this is all seamless and it's MUCH more satsfying.
Also, while watching live TV (for example Wimbledon) you can see on RadarBox what aircraft you hear flying over!
And remember that the live network is updated every 20 seconds rather than every 30 seconds with the delayed, so it's all a lot smoother.
Rod