Some mobs don't give xp, others do... one time i think escape sorcerer didnt give, another time it did.
The 4 assassins that keep spawning in first chapter trying to kill you don't give.
The brain devour didnt, the dude with dire mace in bergar nests (the overconfident one after sword coast boy), the guard captain (friendly npc in the start of every one of the 4 parts in the first chapter)
The priests of helm neither... but well, with the increased xp rate i believe im still leveling faster than normal, but i really wanted xp from the mind devourer, just to know how much it would have been.
In the long run i think the xp system will be flawed in these details, but i believe it will still give more xp than default.
Btw, why the hell some mobs give xp others don't with mods?
Why they don't give at least the default xp? O.o