OK, heres the deal. It arrived today (wow). It will FIT on the Vltor, however because of the Vltor's design, it's not very secure at the top. Just from mounting it and shoulding the gun several times, the top can snag on gear and pull away from the stock. In theory, you could slip it on, and mount the storage tubes up against it and it would be snug, but unfortunately I have my tubes mouted forward for the cheek weld. One wrap of 100mph tape would hold it securely (if you are more into function than looks, like I am).
HOWEVER, it IS a high quality pad, and fit perfectly on my RRA 6-position and my Colt M4 Type II stock, which it was purposely designed for. It locks very securely into the recess above the sling swivel portion of the stock. I would not hesitate to use it on these stocks, but I would recommend one be purpose built for the Vltor.