The Damage output seems to be higher from the Cannons. You can Tank a cube. You are a Captain in a Dreadnought, you can tank that bad boy. But you can easily destroy a cube. Now a Tac Cube is a different story. You actually need to perfect your skills as a dreadnought captain to not only tank it, but defeat it.
The Average PvP player
1) Teamwork and timing is #1
2) You cannot "Kirk It" in every ship
3) You are going to die, just get back up