I am also considering about getting one, but having gone without it for the past 2 years of owning a DSLR... I wonder if I still need one. Of course, shooting portraiture will be easier I guess.
Just curious, for those who has upgraded their bodies from an entry level to say a mid-range kind, does your "reasons" for getting or not getting the battery grip changes? (Entry level, more stability for bigger lenses, better handling, mid range/pro might not get cuz of the much added weight etc?)