Something that's important to consider is if your drives can handle a resilver. Each resilver is essentially reading the entire disk (with lots of asterisks) while setting up a parallel zfs system to provision your disks and using the transfer I described will only read your systems fs once.

You don't even need to use the same system. You can setups a different system, run the transfer, turn off the main system, swap the disks.

It's a hastle but it's an option at your disposal.