CTE is part of the overall TOI make up so I'm confused by that too. I align with TOI either CTE or CTC and then use my tip to create the specific angle. For this to work I MUST consistently connect the cue ball to the object ball, not to "aim" with, to align with so I can have the ability to create the given angle with my tip (target on the cue ball).
I don't claim to be knowledgeable about Stan's system, as a matter of fact he just showed it to me once in Tunica. I thought it was kind of an "inverted" variation of my Ultimate Aiming System from me 97 Video set, however, the PRO 1 seems to be something else. I really don't know enough about the straight CTE to comment, I use CTE on my cut shots and "Center to Center" on my other shots, and CTC on almost all my long shots, even if they're "thin".
I don't think there's a "one or the other" choice there, however, I'm only an authority on TOI, not PRO 1, Stan may be better to answer that question.