Basically not, because the required audit time is the same (as defined by ISO TS 22003).
PRPs shall be established, implemented and audited for any ISO 22000 certification.
Therefore, auditing against ISO 22000 + Synergy PRP 22000 doesn’t require any additional time.
In contrary, the fact that applicable PRPs are already predefined and validated for the corresponding food chain category could justify a (slight) audit time reduction.
The only additional cost is the 150 € annual fee .