When the network bandwidth for a session goes below 5 Mbps by default, display offloading is cancelled. Once the network bandwidth is above the 6 Mbps by default. The display(s) are eligible for offloading again based on the VM priority and Hardware Accelerator resource availability.
You can adjust the bandwidth for enabling and disabling the card but at lower bandwidth rates features in PCoIP software, such as client image caching will most likely provide more value.
Lots of WAN users? Probably not much need for the card. What about GPU’s in the mix? Check out http://gpuauthority.com/