My buddy just picked up a pair of these. Not too bad. Better glass than my other friends $300+ Pentax. Not as nice as my Leupolds or Monarchs for the price but not bad.
I havent tried the diamondbacks but I have the vipers and they are awesome; I got my wife the furys and they are good but a definite step down from the vipers so I would assume the diamonbacks would be another step down.
I have a pair and love them.
For the price they are unbeatable, along with their warranty.
My first pair broke and they had me a pair in less than a week.