Does model number matters?
Sure. Different models = different specs = different performance.
Since most manufacturers have models in their lineup that suck and models that don't, model number matters more than manufacturer.
And as manufacturers try to make their products more profitable, they sometimes cut corners. I've never used the newer '-X' headphones but I'd want to try them before I bought them, because it's not uncommon for the newer "better" version of a product to actually be not as good as the one it replaced.