Here is my understanding ... Straight Suspend does not free the reservations .... Suspend needs to keep the reservations there so you can ensure a resume succeeds. this is just for CPU/MB reservations on the VMs/pools.
Stop will also undeploy, but powers off the VMs ... same as a 'stop' from the UI.
Either of these should be fine for you to perform, since the goal is to power off VMs to take a SAN snap, just that suspend takes that much longer.