@Jerry, but that is not true. As mentioned previously, explanation on how to configure one public IP address for VIP and local addresses for each gateway provided in sk32073: Configuring Cluster Addresses on Different Subnets
One limitation here is when you need to manage a remote location and you have only 1 public IP, which is mentioned in the SK:
It is not possible to manage over the Internet the Cluster when IP addresses Addresses of its members and the VIP address are configured on different subnets.
But if you have the management server somewhere behind the inside interface of that cluster, it will work.