yeah the vampires are my favourite blood summon .
the only other immortal unit ( not leader ) i remember are vanheims swines but they are expensive . but if you summon demiliches instead they should do this almost as well only drawback they don't fly . but in exchange the demiliches are natural life drain casters
and the normal vampires are much worse if stopped through storm .
but you are right the items + the chance on some vampires is really worth trying to bloodhunt .
@graeme i myself find utterdark quite useful in lategame for any nation that is not blood dependent.
ryhleh , pythium , caelum are nice candidates for utterdark too . you can manage the defizit by alchemizing yourself easy and since you are one of the best summoners you have an advantage
hopefully your enemies ( especially e.g. ulm ) rely more heavily on conventional armies .
+ it almost stops bloodhunting in the whole world if you can keep it up with a bit luck