I've been using 2 L Beams (Gimbal), 2 M Multicannon (Turret), and 1 L Cannon (Fixed).
The cannon works fine against larger ships, but in general it hasn't been very useful. You need to keep an eye on the ball or it'll never hit. I considered swapping out for a frag to see if its any more fun to use. Yes, this arrangement will overheat quickly due to the dual beams if you don't manage your rate of fire. If you like to lay out a constant barrage of fire, another setup may be better. I maneuver a lot, and fire with intention. The multicannons on turrets are handy though, as while you FAOff and turn about, while keeping the topside facing the target... you'll drop your heat level, face the target, and be ready to fire beams again.
The cannon works fine against larger ships, but in general it hasn't been very useful. You need to keep an eye on the ball or it'll never hit. I considered swapping out for a frag to see if its any more fun to use. Yes, this arrangement will overheat quickly due to the dual beams if you don't manage your rate of fire. If you like to lay out a constant barrage of fire, another setup may be better. I maneuver a lot, and fire with intention. The multicannons on turrets are handy though, as while you FAOff and turn about, while keeping the topside facing the target... you'll drop your heat level, face the target, and be ready to fire beams again.