To the OP, flip a coin and make a choice. As long as the used amp wasn't exposed to constant under voltage, you should be fine. If you like new and shiny, combined with a warranty and good customer service, just ask yourself if it is worth the additional money or not. Then again, there is always a risk in buying used, so is the savings really worth it?
Now for an aside note: The FfvB - vBulletin Management plugin for Firefox is sooooo sweet. I don't have to see another post by chase007 again, even if someone quotes him.