6-7 seconds is 75% of a 2v2 match.
nonetheless, your build (havent had a deep look, just looked how many points in which tree) seems fine for pvp.
on the other hand, be very careful about 6-7 seconds. a mage that lets you hit him for that long is weak. very weak.
i would believe you in terms of 6-7 seconds hitting him in a 20 second fight. sounds better and more real.
its like me with the mage now, where my frostbolts average crit for 4100 now, but i need 2.5 seconds being gimped and not moving for the cast. i take down people fast, in theory, but it takes longer due to the whole moving around thing. ^^
Come and join on Starcraft 2 as well =]