have not used them but those that I have talked to that shoot in F class to 900m (Calgary, AB) have found them to be really good. They claim that the optics are up there with the best European grades and the adjustments are second to none. Metal to metal throughout. If they are as good as they claim, they would be much cheaper then Nightforce and in some cases cheaper then Leupold. Also, the reticle styles are a lot more useful then mildots.
If you can look through one and try it that will be the only way to know for sure. Check out cactustactical.com for more info.
Yes IOR Valdada scopes are among the very best. I have the literature at home and according to them, the glass is made in a factory in Bucharest and supplies the glass for Ziess, Saworksi, Leica, and a few other well-known scope manufactures. For the price they are the best bang for the buck. I have a set of their medium, and high rings and a set of their bases. Very strong and well made I have no problems with their quality and matches a few of the others out their also i.e. Badger Ord, and Leupold.