I am about to buy and install the Avic-Z110 and have read in these forums that the maps are not necessarily correct in some cities. I have read in other sections of this forum that others have downloaded and use maps by Navteq (which is what garming uses). Has anyone here used other map files besides what is comes out of the box from Pioneer?

That is not possible with the Z110BT. There is no way to update or add maps unless released by Pioneer. The maps it comes with are fine, no navi unit is perfect. I have seen some of the same type of problems with Garmin units at times.