From talking to you guys and a few of my friends I think I am going to go with the 715C for right now, and then invest in the 715T.
From what I was told the 920T really wouldn't fit my intended arsenal, and the would 715C give me something below my 505T that is more controllable than my 607A if I need to ball down.
The reason for me not going with the 920T is due to my 505T and 920A, and the fact that I plan on getting the 715T. Currently, 920A I have is completely dependent on the surface I'm bowling on. If the lanes have friction down lane, even with long oil, I can use it from the beginning and it's a fair amount stronger than my 505T. However, if the surface is slicker down lane I have to use the 505T in order to make me a spot for me to throw to.
Once again thanks for all of your throughful comments.