Katie,
If you are bringing up pigs for food, you will be taking them to slaughter when they are about 6-8 months old. At this age, they will be around knee height and weigh somehere around 60-80 kilo's, so about the same as an average human (12 stone ish) - so imagine a human down on all fours!.
Unless treated badly (and obviously you won't be doing that!), pigs are gentle and friendly animals, and the in general terms the most risk you are under is being pushed over into the mud by a pig rubbing its ears on your leg, or enthusiastically arriving for supper!
So do go for a Kune Kune if you want to, but don't limit your choice on size reasons, all the "rare breed" pigs and rarebreed crosses will be good compnay and make cracking eating !