There is no IPV6 support in the proxmox module, the module itself is very basic and does very little, it's pretty poorly written. Not sure about the soluzvm module I have not tried it.
Proxmox module will allow you to do the following
provision openvz automatically (must increase sleeps between the provision and start otherwise the initial start of the VM fails)
provision KVM kind of
shutdown/start a vm
see basic stats (graphs)
Things it can't do, and or are completely broken
Console is completely broken
Shutdown / reinstall ( reinstall fails due to "sleeps" between the stop/destroy) rather than polling for status, they hope tasks finish before the next starts
Can't change host-name
Can't add more than 1 IP
When a user cancels that IP does not get re-inserted into your available pool
Can't change root password
no way to limit bandwidth
"netspeed" seems to do nothing their way of limiting throughput per vm
Very difficult to find your IP address (as a client)
Provisions the VM with a default template instead of allowing the customer to select the OS when they sign up.
The list goes on, it's .. pretty bad, even if it is free.
honestly, this module in it's current state is not something you really want to use. I would assume the SoluzVM module is much much better.
