I'd just like to say the plasma cannon is absolute bullsh*t.
I'm a middling player. If I'm a defense technician I'm probably somewhere in the bottom half of the rankings. Otherwise I'm usually in the middle of the pack.
I've been playing a lot of Capture & Hold lately though, and I do enjoy playing the brute in that case.
And I must say, the first game I ever scored #1 was my first game with that damn plasma cannon. Slow reload but an insane fire rate and projectile size. And usually instead of reloading I switch to the spinfusor for 5 seconds or so and go back to the plasma cannon when it reloads that way.