Last week i was dealing with a V10k load sharing project,
v10k does not have load sharing feature so we put an alteon switch front of 4 v10k appliances,
our tests was fine,sessions were sharing along the appliances with round-robin.
Policy Server functions on it's own independent of the Policy Broker so i have left the 3 roles PS,US,FS on V10Ks
Although you can define one policy server during the installation of logserver, we have seen that we can successfully get logs from the 4 policy servers simultaneously,
also another issue was to upgrade v6.3x to 7.5 , dont forget to follow v6 to 7.0 to 7.1 and finally to 7.5