I don't think people would prefer the map to jump to a new place just
by switching maps. It's all too easy to accidentally click "CalTopo
USFS" when you meant to click "CalTopo USGS", and the mistake cannot
be undone. It's a lot to expect users who don't want to lose their
place to know the bounds of each map.
I suggest, for bounded maps, that when the current position is outside
the range of the map, you show a background overview map of the world
as you do in the USGS Topo layer.
I agree you don't want to remember the last location for each map.
Only the current location is what matters.