I think the browning out is not related to the axanthic gene at all. I think the only way to get rid of the brown is to cross in morphs with a lot of yellow that do not tend to brown out. So an adult axanthic that didn't brown out would probably be an outstanding normal considering its clean yellow parts. By that, even a browned out axanthic should be capable of doing nice combo animals.
I have some axanthics myself. A brighter and a darker axanthic female. And a weird Pastel/Ax. Shooting at fire combos will be one of the first things I'll do. Imagine an Superfly/Axanthic or a Dragonfly/Axanthic :rolleyes:
Really nice animals by the way...can't wait to do that pairings myself :-)