From what I understand, whatever shell Bauer decides to use, the fine tune fitting will come down to the commercial molding process the shell is undergone to wrap around your 3d scanned last. Custom pro mic uses the traditional c d e ee width measurements/shells. Not sure if they will adjust the facing to be optimal after this process so you don't have either too much or too little wrap after the shell has conformed to the last.
On a side rant, their retail custom is such a joke since you are strapped to their fit system. Like for me, my left is a 7 fit 1, but my right is a 6.5-6.75 but in the same volume as a 7 fit 1. I've tried a 6.5 fit 3 and 2 and both don't work as the fit 3 is too much volume and the fit 2 is too tight. But I digress.