SonyEricsson Hardware and Firmware Definitions!
Setool lite is to apply patchs and for flashing. Xs++ is for flashing only.
If you do right , then it`s a minimal risk , but you should always make a backup of GDFS.
XS++ 3.1 Guide-Flashing, Customizing, Recovering
Flash your phone and How to apply or remove patch using SETool 2 Lite
General Information about Patch-Unlocking (start here if you want to unlock)
Remove SIM-lock patch generator
Nice day