I've a chinese X-GPS model: GPS-S570HD MTK Win CE 6.0 system and runing iGO8 v18.104.22.168799.
The maps in use are:
Europe 2011.12 TomTom all rights reserved 
Israel 2012.03 GPS and More 2012 
During my last visite in Israel, my X-GPS not always show the logical routing, it makes me do every time an unneeded detour.
Moreover, it directing me to an opposite way (north instead south direction for instance). As I took the correct direction south, It never recalculate the route and always asked me to make a Uturn.