Older battery grips like the MB-D100 included a voice recording option as well on the battery grip and including the ability to use 2 batteries simultaneously at the same time and allowed switching of any one dried cells with a new one without affecting camera operation.
If you don't have the cash, get the camera first, the grip is pretty much secondary to some.
Personally, I like the feel/build it gives to the entire camera as a whole and with my constant shooting of portrait orientation, it's pretty good to have one.