I have the Coleman version of the Coghlan's hammer. There just isn't enough weight to it to drive stakes through rough ground or rooted earth. After my last camping trip struggling with that hammer, I was planning on picking up a cheap hammer at HF, HD, or Lowes. That being said, I don't have a hatchet in my camping equipment, so I'm liking that idea. I don't think I want to go cheap on the hatchet, however.
That Snowpeak hammer looks great, but that's more money than I'm willing to spend on such a specific use item that will see infrequent use.