I bought a Sinister for my 17 year old son a week ago, and he used it in competition yesterday.  I'm not into specs and such, but its drilled pin above the ring, and a weight hole next to the thumb.  He throws about 19 mph.  He hurt his back just before practice on Wednesday, so he was babying the ball.  I told him to just work on being accurate...so he does that and had a series of about 630 for 3 games.  Pretty good, and the shot was all messed up, no fresh oil, and his average is about 188. 
Yesterday at the competition, his back still bothering him and still not up to speed, he throws games of 248, 247, and 243 for a 738 series.  Would have been higher if he didn't throw a ball straight into the gutter during the second game in the tenth frame, lol. 

He stayed with the Sinister for all 3 games, and just adjusted as needed.  I was surprised that he didn't have to ball down, but he's like that.  He'd much rather move than ball down.  The ball was just clearing the heads, grabbed the lane, revved up, and Ka-boom!  Great ball!