Go-Pro Vs Contour comparison

Go-Pro or Contour? what should I get?  That was a question Kevin Lu one of our Racefriv contributors asked me.  Actually he specifically needed to know about underwater usage to compare to just getting a dive housing for his Canon S100.  He texted me, but i'm not the sort of person who can answer a photographic related question in 150 characters.  So Kevin, instead of just answering you alone, in a series of badly written texts, here's the long James May answer!  Hit the jump for more.