Do I need a pfsync interface if [pass] filtering is limited to localhost? (a services pfSense)

[senseivita]

I have a couple of routers with filtering still enabled to prevent inter-VLAN routing, so I guess they still are technically firewalls, but they're not the default gateway for anything. Would I still need a pfsync interface for them if they are made highly available?

Blocked traffic doesn't have states, so nothing to sync...right?--Is it different in HA setups??