WE've done both for two trips. The first was wonderful, and our experience at PSB was better than CRT. For the second, the PSB breadfast wasn't as magical as the first time around. It may be my personal pet peeve, but I really dislike when Mulan is played by a nonasian CM. My daughter is asian and there are so few characters/role models available to her that it's a huge letdown when one looks obviously caucasian.
The positive side of doing the two is that it is never too much for princess lovers. Also, I was impressed with the ability of the princess CMs to remember my DD and DS from a breakfast at CRT!!!
This upcoming trip will be the first time we are not doing both breakfasts and I am unsure if it was the right thing to do. DD is now 6.5. I'm not sure how many more princess years may be left!!!
Good luck with whatever you decide to do!