Derek,
In you file for:
"This is actually possible with PS_B set to divide-by-6 (400MHz). Y6 / Y7 divider could be set either to 4 or 5 to achieve 100MHz / 80MHz switchable. Try switching the frequency in Y6 / Y7 boxes between 100MHz and 80MHz in the attached file".
What do you estimate jitter RMS ps max to be? - Patrick