Yeah, I think the graphene coating thing itself is more of a convenient marketing thing, with likely very little sonic consequence.
However, SEAS did re-design the driver in various other ways for better performance (which is why Jeff Joseph had to re-design the crossover).
People comparing the original vs graphene versions of the Pulsar and Perspective speakers seem to have pretty consistent impressions - "better" bass in terms of more punch and tighter, and slightly clearer midrange, a bit more mellow in the highs.
That said, I can imagine the graphene upgrading making less difference in the Pearl vs the Pulsar and Perspectives. The Pulsar/Perspectives rely entirely on the new graphene driver for the mids and bass, so any difference would likely to be noticed from the original drivers. Where the Pearl only changes it's midrange driver to graphene, and has a couple bigger woofers doing bass.
