I had one. I think I sold it in here. It does what it advertises for the most part. It adds a significant amount of weight and a good bit of length. i didnt like the bulk and it was overkill for me so I got rid of it. If I remember right, I couldnt get the cheek piece exactly where I wanted.
Would it be easier to just get better fitting rings, or is the scope objective huge requiring a high mount?