I'm considering upgrading from a 270c to a 3040 (all aggrs, no traditional vols).  I'm wondering about the proper procedure to swap the heads.  Here's what I'm thinking the steps will be, but I'd like someone to confirm or let me know if there's a better way to go about it...

on 270c...

change root vol size to accommodate 3040 (both)
upgrade ontap to 7.2.2 (both)
modify /etc/rc for different interface names (both)
record ownership info, which filer owns which disks (both)
disable cluster
shutdown both heads
replace EFH mods w/ ESH2 mods

on 3040...

attach shelves to both 3040 heads
boot 1 head into maintenance mode
remove ownership on all disks
take ownership of only the disks that were previously owned by 1st filer as recorded in above step
run "storage release disks"
run "mailbox destroy local"
shutdown head
boot other head into maintenance mode
take ownership of only the disks that were previously owned by 2nd filer as recorded in above step
shutdown head
boot 1 head, confirm things look good
boot other head, confirm things look good
install 7.2.2 for 3040 architecture
apply new licenses
enable/test failover

I think that might work, not sure.  As I see it, the biggest risk is missing a disk or 2 when assigning ownership.  My guess is the filer would attempt to recover the aggregate by rebuilding on a spare.  Is there an autorebuild option I can turn off that would allow me to recognize that a have missing disks, boot back into maint mode, and fix manually?  Just trying to uncover my biggest areas of risk in the procedure and mitigate them if possible.  Thanks.

JeffD