You can migrate VMs from one DS to another DS when aVM is shutdown.
Why not assign every Blade to every exising Virtual Disk (of the Perc8 of course) and you have shared storage and HA and vMotion will be working as expected.
If a ESXi runs more than 60 days its not possible to switch back into eval mode. If you perform a major release upgrade like going from 5 to 6 the host will goes into eval because you need new licenses.
Thanks for the answer.
I can shut-down the VMs but I would like to avoid any downtime at all (or minimize it as much as possible)
Existing VDs on Perc8 will be deleted and recreated from scratch (several RAID5 volumes unified into single one, RAID0 for transaction logs of MSSQL and other lovely things)
Unless I'm mistaken, the Essentials Plus edition (v5.5 and newer) supports changing both host, and storage from the Migration wizard in the vSphere Web Client. With a vMotion network in place, this can be done online, even without shared storage.