and they still have to use Deception to change their voice
For the record, I don't think the Changeling is inappropriate, I'm explaining why someone might take that position.
Their ability explicitly allows them to change their voice: "You decide what you look like, including your height, weight, facial features, the sound of your voice, coloration, hair length, sex, and any other distinguishing characteristics."
Keep in mind the Warforged also has a Feat that further improves his AC and gets them some goodies depending on the core. Wonder what class might turn into the most durable tank with that. Only feels a tiny bit wasted on a Barb if you go for reckless, even if the gap between your normal AC and WF is quite high but with advantage not high enough that the nasty stuff later on wont hit you anyway I presume.
Keep in mind the Warforged also has a Feat that further improves his AC and gets them some goodies depending on the core.
I am refering to the Mithral Protection Feat from the Archetypes PDF for Eberron? Was it kicked?