Originally Posted by Bogalu
Still I wish they made them metal because after a while the plastic absorbs the flavors and eventually ruins the diffuser.
I've never heard this one but wouldn't be surprised in the end. Also keep in mind that most KM/Syrians will have a welding nut on the end of the downstem which provides some diffusion. If you're looking for your hookah to be silent, a heba/homemade diffuser would probably be the best route.
As far as KM/Syrian. Go with whatever you like the most. As long as its not a cheap Chinese stem, you shouldn't have to worry about rust with proper maintenance. Just get a stem that you'll look forward to setting up because you like the way it looks.