I tried the cannon build, it's fun to play with but IMHO it doesn't seem to do as much damage as beam arrays. I still prefer use cannons in an escort/destroyer, I have a plain Advanced Escort/Prometheus with AP DHCs that is my favorite for STFs.
I'm going totally by memory, but here's my layout. I also have the spacebar set to activate all abilities in Slot 7:
Fore: 2x phaser BA, 1x dual beam phaser, 1 torp (Breen Transphasic Cluster Torp)
Aft: 4x phaser BA (Full MACO Mk XI or XII, I have a mix.)
Sometimes I swap out the Phasers for Antiprotons but the Phasers seem to do more, maybe because the Phaser Relay consoles have higher specs than my AP consoles.
MACO Shield, Borg Deflector and Engine.
Eng: 3x Neutronium Mk XI, Borg
Sci: 2x Field Gen mk XI (Blue)
tac: 4x Phaser Relays Mk XI (Blue)