the fact that i believe the stock turbo is too small to actually benefit from a BOV.
This kind of makes me think you don't know what a BOV is or does, or maybe you just wrote that wrong?
Any turbo needs a bov or a form of pressure release, and our car comes with one, just it recirculates and is called a CBV. So our turbo even though it is small will benifit from a BOV in that any turbo will as it will extend it's life, that is the purpose of a venting valve (no matter what you call it).
It really has nothing to do with performance (which it sounds like you are gettinga t when you seay benefit?). Though when you do go aftermarket, they generally have stronger springs or higher boost holding capabilities.
So if that is what you meant.... there is no reason to get a BOV on this car stock, as it doesn't produce enough boost to make the OEM CBV in-effective, then I would agree with you. As havinga CBV, there is no reason at all to have a BOV and there is no benefit at all. But if you get rid of the CBV, then a BOV is not only beneficial, but a must on this car.
As far as the noise level, the higher the boost, the louder it will be, the smaller the vent, the higher pitched, the larger the vent, the lower pitched and just like any musical instrument you can make it louder by making a bell type housing on the end. It has little to do with turbo size, and more to do with boost pressure.... which is kind of related to size, but more spool time than size untill you go really big.