After looking at their site and reading the specs, I don't think I would use it!
Like the Dodgeman states, there is no heavey duty spike. The max weight load is 480lbs. I don't think that is any bargain.
What is your soil like? If it is easy enought to pound down a spike, it should be easy enough to dig in. I think I would still rent a gas auger from a rental center. (it saves so much time and it should be cheap money.)
You are going to need about 13 holes depending if you are going to have a gate in it or not. I would dig a 30" depth and cement 2' of it.
That's my thoughts.
Good luck, Jason
ps. Whould you be holding the spike or swinging the sledge hammer?