I have never thrown the 505A, but I can speak to the quality of the 505T.
The 505T will probably be able to replace your Gamebreaker if you take the ball to a similiar surface. However, if you leave the 505T at it's box finish the ball is pretty much one of the best balls in the midlane I have ever thrown. What makes the ball so great is that even with all that midlane it still reads the backends really hard. I think what really makes this ball amazing is how long I can stay with it considering it's relative strength. Unless it's a second shift late league, I can stay with it pretty much the entire night, and the deeper I get the harder it comes back.
My 505T is drilled pin down, below the fingers on the grip line, with the MB next to the thumb with a flare increasing hole.