Justin, I like what you've done with your PowerShell module. I have another way that might be helpful for setting the PSP to round robin. Checkout this script here : Set VMware RoundRobin PSP through PowerCLI
It will loop through all of the ESX hosts and any attached Nimble volumes managed by the VCenter server. It will then set the policy to round robin, IOPS per path to 0, and set a rule so any new Nimble volumes will use round robin automatically.