Hi Bob,
you don't miss anything. This feature is generally "bad". I already many times discuss this with one use "joeloc" and may only confirm, that this way for selecting maps, isn't perfect and should be somehow "more automated". For now, there is no better way then this one you use.
Just one info. When you add new map from mobac into locus, that you may notice that Locus do some "initialization". One part of this is setting of this map center, so there should generally be no reason to change this value except fact, you have really huge maps that do not appear in quick switch list
edit: and btw. you may all information (tutorials/manuals) that may be useful for public, put here
http://docs.locusmap.eu/doku.php/community:main