But, to give an idea of scope, here is the rough map (note that if an island only appeared on one map, it got averaged out of existence) made up of all the other maps. The heavier lines (I tried to clean them up) are usually places where the same bit of coastline was the same map to map.
To show the scope of the information problem, I whipped up a quick overlay on this estimating the amount of information I have for each area on the map, ranging from 0 to 10% or so (nothing more than a few names of cities and places) to greater than 90%, where I have the land mapped out over large time periods, huge active campaigns, etc. On this map, black represents information, and green represents a lack of information. I tried to make it out in rough blocks:
So, suffice it to say, there is a LOT of room for expansion by other creators on the map.