Concrete Footing or Concrete Blocks For Footings
You will have a more stable deck if you go 48" into the ground. This will significantly reduce the stress on the house and deck at the ledger board. In my deck experience (I used to rebuild decks) I would rather have a pier in the ground. In some of the estimates the ground goes through 1,000 freeze thaw cycles in a hard winter here in the Midwest. That means that your deck will move slightly up and down with each cycle. This would matter more or less depending on the soil type and the size of the deck. It is a bit more work to drill the piers and pour the concrete but I think it's worth it. I haven't read all the specs on those piers but when they first came out I don't think they were advertising it for as tall of a deck as your wanting to build or that your neighbor has.