I thought the FantomG had a sampler too? And, if I remember rightly, it not only imports it's own format (an extensive Hollywood quality library exists for Roland, back from when the Roland sampler racks ruled the roost) but I thought it imported Akai as well... (largest format library in the world)

A $350 expansion board isn't the ONLY way to get new sounds into a FantomG... But it's the only way to get altogether NEW capabilities into either the MoXS or the FantomG. That's because each board isn't just samples, it's a whole different synth, with different capabilities (all the modeling stuff on the E. Piano and TD-Drum kit boards, and SA and newer brass voicing capabilities on the new ARX-03).

Kind of what Yamaha USED to do with the expansion boards for the MoES, which for some unknown reason they dropped...