Small beam turrets have the same DPS as medium pulse, similar power drain but half the weight and track small targets better, if you want to use all weapons together you need to limit the power requirements, as a 6A power dist will run 3 MW weapon fire, do the math

, m-cannons in the non turret positions also works well but you'll soon run out of ammo.. so back to lasers.
You can either have long firing duration with lighter weapons or shorter duration with heavier but you still have just 3 MW to play with whatever approach you choose, remember "ye cannae change the laws o' physics" LOL
Seriously though I've tried a lot of FDL builds in Beta's and the PA's and cannon's are great as long as you can find a big enough target to hit but you waste a huge amount of time trying to line up a target but once it starts maneuvering... switch to lasers or m-cannons if you want to get a kill in a sensible time frame