It looks like Linux might be about 3% of our sales. From a profit standpoint it probably has not worked out, but I think supporting Linux is nice for other reasons (open OS, don't like the direction Windows/OSX are going, good community, etc).
Unless I changed to a new engine that didn't have Linux support or radically changed the current engine, there really isn't a reason to drop Linux support. I've already done the hard work.
Depths of Peril, Kivi's Underworld, Din's Curse, Drox Operative, & Zombasite