I prefer auctions where individual auctions are given more importance and are alerted in chat. Also AH is nothing to do with auctions. It's just a market where you set a fixed price and wait for buyers, but with auction you can get higher prices based on the demand. Auction is much better for people who auction to make money. AH only benefits buyers and you don't know when a good deal is up for grabs, so the nolifer campers who don't even do much other than pile up goods for ranks would benefit more.
Also I think the Special Gunpowder is not needed anymore. It was useful once to keep TNT prices high. But now I think that's not an issue anymore. If it's still an issue creeper spawner price could be raised to 1000 DC however.