A lot faster and a light higher than I feel comfortable piloting ;)
I am interested in this too.
I'm considering some high speed vehicle tracking (my main reason for starting my ever first quad!), which will be done automatically on a "follow me" principle (no idea how to approach this technically yet!), but the quad will need to be able to reach around 40-45 mph equivalent ground speed, while maintaining a flying time of at least 6 minutes (not including takeoff and landing).