That's off the stout tap on a nitro blend.
I also used half of the vanilla which was enough for me.
If you peruse the thread... or was it the other thread, I think that you'll find a wide variety in the amount used. You'll also see that there are many types of vanilla used and that contributes to a wide variety of intensity and robustness.
Some used real vanilla, mexican vanilla (which may or may not be real but varies quiet a lot in strenghth) and imitation. Others made vanilla with vanilla beans and either rum or vodka. Mine was made from rum.
I think it better to add too little than too much. Some people got lucky, others like rdwj didn't fare so well.
I like mine alot, alhough this is not the type of beer I normally like. Part of the appeal is doing something different.