Hi Rob,
Following responses to your questions:
if CA supports a hardware load balancer between the policy servers and the policy stores?
R: No, this is not supported. In fact, what is the purpose of load balance between policy store? When policy server startup, it load most of the data into cache so it won't get to policy store that frequent. I would said the load to the policy store is minimum and don't need
The documentation only refers to failover to replicated secondary store. Is failover the preferred and more stable deployment?
R: Yes, failover is preferred. Due to the nature of the policy server load objects from policy store, I think is better to load all objects from same store (unless the primary down then failover to secondary) to prevent mix up of data due to the replication issue on policy store.
Hope this helps.
Regards,
Kar Meng