Looks good guys! I'm going to try this out as soon as I finish running stupid huge database jobs.
One observation (before running it)...
In multimap3.def you have not specified values for size0, size1, size2 and size3.
As I said, I've not tried it yet but I'm guessing that when I do the loading bar isn't going to work.
The size values are rough guides to the texture memory used by the map in the four quality modes (low,med,high,ultra). Without those you don't get meaningful values in gui::map_loading.
See
http://www.modwiki.net/wiki/Mapdef_(decl) for info on size calcs.
EDIT: Stupid BBCode - the URL above should have the _(decl) part included in it. Just go here instead and click on the mapDef link
http://www.modwiki.net/wiki/Declarations
Sim