I ran a test to compare the quality of PPS outputs from a DIO (used as GM) and an FDELAY (used as slave) White Rabbit SPEC/FMC combinations. Here is the phase data measured with a Time-interval-counter. The nice clean traces are derived from a H-maser. We then lock a BVA (internally 2x multiplied to 10MHz) to this PPS signal. The GM node is locked to this 10MHz signal.
The average of each trace was removed, and the traces are offset for clarity.
The Allan deviations look like this. Both the DIO and FDELAY PPS outputs have allan deviations about 5x worse than the BVA used as input clock for the GM.