in all honesty forget three maps etc, just get one done properly and use an electronic boost controller instead.
a good map should be a 'safe' map anyway, you don't want it too 'safe' as you'll lose economy and power at the same time.
a good mapper will get it as good as it gets with one map.
i've got megasquirt and i'm only doing one map and if i change something, say cam, then i'll sort the map again. no point in switchable unless you plan to move the ecu from car to car.