Speedfusion / PepVPN is there an overhead difference between 1 and 2 active WAN links?

Product Discussion Peplink Balance
1

With a Balance router connected via SpeedFusion to a Fusionhub, is there a difference in overhead of the speedfusion connection between:
1 WAN link
1 WAN link active and 1 WAN link in lower priority
2 active WAN links