from the software perspective its just ram addresses from xyz to 123, so the CPU will be the factor
but the hardware will have a bus route (makes division of the full RAM address range) for quick access to the address that is the second chip which is the only thing that makes 2x4 just a touch faster then 1x8
basically two lane road to the full addresses vs a 1 lane road
it will probably limit 3rd parties for a short time, until they purchase the tool that is required
or someone reverse engineers a tool that doesn't violate some trademark
these things never stay in one parties control for long