Know shooters who use them for F class out to 1000m. They say the optics are up there with Zeiss and Swaroski (sp). All adjustments are metal on metal. Reticle does allow for good elevation and windage adjustments. Depending on the model, they have a fair amount of internal adjustments.
Just keep an eye on the specs as they were designed for military and tactical work. some models will not fit our needs.
So far their reputation is solid. However, I have not used one myself.
Good luck...
Jerry