First, in case you haven't figured it out yet, arguing with Coral Pro is like playing tug of war with a puppy... the harder you pull, the harder he pulls back, and he never gets tired of it.
I personally don't believe that using a line improves one's alignment, but I don't have any problem with anyone who does believe it.
I regularly play with guys who use that method... some of them are good putters, but I've rarely met one who putts any better than I do. In fact some of them are terrible putters, and will do almost anything to try and improve. I have played with guys who putt better than I do, but not because of any line on the ball, they just happen to be good putters.
Good putters are good because they have good fundamentals, and a line on the ball doesn't change that. Bad putters are bad because they don't have good fundamentals, and a line on the ball won't change that either.
