AD9545 OCXO recommendation

The "AD9545_BOM_05-040513-01-c.xls" recommend OCXO "OH300-61003CF-010.0M" from Connor Winfiled. This is a 10MHz oscillator.
According to the AD9545 data sheet the minimum system clock is 16MHz, but with a note: "Support of oven controlled crystal oscillators (OCXOs) < 20 MHz is possible using the auxiliary DPLL for system clock frequency compensation".
Why is the recommended OCXO 10MHz? Would it not be better(easier) to use an e.g. 20MHz OCXO like "OH300-61003CF-020.0M" from Connor Winfiled?