Hi @teamits hehe well actually I do because the SYNC network also has a few other clients behind it that require the VIP such as LAN.
Basically as I mentioned on the above posts, I chose an already existing network for SYNC that has two other clients beside the pfSense machines. This is a secured network and these are administration machines with restricted access and little traffic.
The documentation recommends a separate network, as I see it, for two factors:
network availability and load
privacy and security (as passwords aren't really encrypted)
Since the chosen network complies with these requirements, it is a very restrict network with very low traffic, this network was used and hence the interface used for sync has a carp vip.
Anyway, all configurations: HA, Interfaces and DHCP server etc have the peer IP directly where it belongs, not the CARP VIP.
I expect this interface to work alike the other interfaces (LAN/DMZ7DATA) etc.