Xotic 4-16 x56mm are very good scopes. The one I have has good glass. Compared it to my Nightforce 50mm and could make out 1 size smaller on the Zeiss chart (both at 15x). Tracks great. It is a huge scope- bigger than Nightforce NXS. They haven't made any scopes in years. I went to their old webpage and hit the contact icon and nothing popped up. I don't think they are in business any more. Very good reliable scope but probably can't get them fixed if one goes down.
They were a great setup for the money, but the lack of backup would keep me from getting one today (unless it were a great deal, then I might bite anyway).