Linux drives are pretty easy to migrate into new physical servers.
Just pull the drive and put into a new server.
Sometimes you need to update the UDEV, but for the most part it works.
I do not know if FreeBSD/pfsense drives can be moved around like that.
Or would it be better/faster to install a new pfsense and reinstall all the rules ?
I have an installation on a USB stick, works fine with different devices, should be no problem with a hard disk, I guess (i386/64 should make a difference, however). Do a backup of your config before, just for the case…;-)
I've physically moved Drives for pfSense but really bar far the simplest method is to take a configuration backup. Install pfsense on the new hardware and run the configuration restore..
In fact when I'm building my pfsense boxes I have a standard configuration starter which I put on the USB installer so when they boot up for the first time they are already half way done.
I'm curious if different MAC addresses don't mess up the if configs.
I had a bunch of trouble with Ubuntu distros.