I'm missing a vital tool in my box, an air hammer. I've always like IR air tools, but I'm not so sure I need to spend the big $$ for their hammer. Is there an advantage to a better hammer? Is there a serious difference in the operation of say a $39 Sears one to a $89 IR heavy-duty? This is something I really don't understand how to make sure you get a good one. Every one I've ever used was loud as hell and did the work, and the quality of the chisels/attachments always seemed like the most important thing. I don't want to end up with crap though, so what do you think? What kind of air hammer should I buy?