I've been using one for years. Have a 15 lb saved from 3 years ago (for when I have to go back down in weight) and bought TWO more in 16 lbs. One is drilled pin next to ring finger and one is drilled pin over center of bridge. MB is always around the thumb, usually under or on the track side.
I can use mine to get out of any number of oil pattern transition problems and on almost any light to medium-light pattern. It has possibly the most versatile cover I have ever used. I have had it anywhere from 1000, 2000, 4000 Abralon matte finish. And 600 grit US, 2000 Abralon and 4000 Abralon polished. Current balls are 600 grit US (green nylon pad) + Storm's Xtra Shine and 2000 grit Abralon + Valentino's Snake Oil.
With the matte finish surfaces, it can smooth out many wet/dry, over/under conditions. 4 or 5 years ago when Nationals patterns were drier in singles and doubles, I used a 2000 Abralon matte ball to play between 4th and 5th arrow.
--------------------
"None are so blind as those who will not see."