Don't let the pictures fool you, this is a tiny turret, less than 100 mass. Despite this, it packs a serious punch, has good range and is self powered. It fires a double shot every four seconds, each doing 6000 damage. That is enough to obliterate an advanced armor block with full bonus armor hit points 'and' full pierce protection, and then still have plenty of power left to mess up a good depth of system blocks. If a ship is not protected by such pierce hardened advanced armor, this weapon will make very deep holes indeed.
It measures 20 blocks long, 15 wide and 8 high. It will stop it's own declination before it gets so low that it might hang on the hull. It requires no holes in your ship deck, just a clear expanse sufficient for it to rotate. It requires no power, as it is completely self powered. Add a few of these to your ship and you'll be making Swiss cheese of pirates.
Sadly I do not have much of an artistic streak. I do not design my systems to be pretty. However what I build tends to be extremely functional. This sort of turret can give a small, otherwise under powered ship, some serious firepower, especially if you place a few of them.
Be aware that in an effort to keep the turret light and affordable, it has minimal shields itself, only around 5000. relying mostly on the ship's shields for it's protection. It also has little in the way of heavy armor.
It is literally as effective as a turret can possibly get for it's mass, without discarding it's hull cladding all together. In that respect, I protest your assertion that's it's performance is 'average'. For it's size and mass, it's performance is as good as it gets. It is literally impossible to get a turret of this mass to perform better than this while still having it self powered.