Some additional considerations --
- You may also have to make PF configuration changes for changes in NICs. Usually, this is through macros near the top of your pf.conf file.
- Different generations of computers, even within the same architecture, may have different limitations on boot block locations, as per FAQ 14.8.
I just moved a server's drives and one of its NICs to a spare computer due to RAM or power supply problems. I did have the issue where I'd forgotten to revise the PF configuration.