Oh man, I just grabbed the ReLoad utility the other day, and decided to rip all my Akai CDs to Reason format. When I finally got them ripped, I opened up one of the 128MB Piano patches. "Oh," I said to myself, "these patches split the keymaps, and I remember when I merged these on the Akai to one single piano patch, it was a several hour nightmare of loading the new sections, copying things over, and then saving the beast back to disk. Man, I don't want to have to do that again!" Then I sat back and thought for a second and said, "I bet those Prop Dudes were pretty smart, and if they were thinking like me, they'd let me do things easier than that sampler." So, on a whim, I opened a second instance of NN-XT, loaded the next keybank in that sampler, selected the samples, CTRL-C, back to the first NN-XT, CTRL-V, and Voila! There were two keymaps in one sampler. Five minutes later, I had all six keymaps on one sampler, after which I saved it out, reloaded it to test, and was up and running.
Now that I know it's this easy, there's no way I'm going back to using that hardware sampler. Anyone wanna buy a S6000?