[Pippa]

I've just been doing a little reading and now it does make sense

Monitoring Critical Devices (cphaprob list)
When a critical device fails, the cluster member is considered to have failed. To see the list of critical devices on a cluster member, and of all the other machines in the cluster, run the following command on the cluster member:

cphaprob [-i[a]] [-e] list

There are a number of built-in critical devices, and the administrator can define
additional critical devices. The default critical devices are:
• The cluster interfaces on the cluster members.
• Synchronization—full synchronization completed successfully.
• Filter—the Security Policy, and whether it is loaded.
• cphad—which follows the ClusterXL process called cphamcset.
• fwd—the VPN-1 Power daemon.

So it does show if full synchronisation is working.
fw ctl pstat also tells you abut sync status too though.