In the neck position, it didn't make much of a difference other than the loss of sparkle, when soloed. But it seemed to overpower the AXY at the bridge, rendering the pan pot quite useless.
People seem to agree that you can combine a Fatboy at the bridge with an AXY at the neck, but not the other way around. A set of Fatboys should probably work fine.
Perhaps a short comment about my playing conditions - I play only in our living room through a SWR Workingman's 12, with the volume pretty low. Perhaps with a louder rig, in a band situation, the loss of sparkle is less of a problem.