I keep saying this as well and get jumped on by the fixed wep PvP purists.
Time on Target is the most important factor. You do less damage with turrets, but they are on target a lot more resulting (in my mind) with more damage long term. Ships with limited agility can use turrets effectively. A pair of C1 turreted beams can keep shields down nicely as other weps take the hull apart.
Anyone who's strictly a fixed weapon user is either a top-notch roleplayer, commendable challenge enthusiast...or kidding themselves. They simply are not the "l337 if you git gud with them" tool that they've been stigmatised as, and gimballed weapons are often a potent foe in the mitts of someone that knows how to use their extended hit angle to their advantage.
Now as turrets go they might well catch out a less experienced player, but if someone knows how to move they start losing that time on target advantage. Unlike gimbals, turret tracking is
slow. If you can evade a chunk of the damage while sustaining an assault using a fixed/gimballed loadout, the turret user is now in a game of numbers it can't win - and in some cases loses situational awareness if the turrets have to be layered on top of the ship.
Don't get me wrong...I, a PvPer, can reveal I have used turrets! (yes, shock/horror/gasp/etc). They landed on top of my iCutter for some lazy CZ massacring; I quite literally hit a point I'd mashed so many NPC ships I wanted a break from putting effort into it. Got some turrets engineered on the quick, put 'em on top, and it turned out to be a fairly effective tool against NPCs, and even won me a fight against a PvP FDL. It didn't fare so well against another iCutter though, using MCs; his DPS was just too high for turrets to keep up with.
Put it down as a learning experience, and they're gathering dust again...
You see, i know you like PvP, but its all about boring meta. With PvE you can give yourself a challenge and do all sorts of crazy stuff that just won't fly in PvP.... although i think the build i'm looking at could be an annoyance for PvP if nothing else
Come now, that's a little sharp as an analysis.
You can actually get away with pretty much any intelligent loadout in PvP if it's either for planned duels or, conversely, areas like CZs for completely unplanned PvP. I'm on an unplanned break (sobs) but before that I spent most of my PvP time in a FGS, iCutter, iCourier or iClipper, and with some very interesting loadouts.
Where it gets soggy is "PvP expected" areas such as CGs. Typically that involves either FDLs or 'vettes using either the bog standard meta loadout, atm I believe long range and rails, or whatever cheese loadout is viable...currently heat cannons or shield strippers and packhounds. Basically a conglomeration of the worst of the engineers.
I like my PvP, but for that reason I stay clear of hotspots such as CGs when I actually want to fight.