Uhm, I think I may well have forgot to disklabel the raid0 device when I 
was setting up my RAID-1 array, like `disklabel -r -e -I raid0`

(root@bone)/root# disklabel -r raid0
disklabel: Invalid signature in mbr record 0
disklabel: no disklabel

The newfs on rraid0a still worked, however, and made a filesystem. I've 
simulated what I have managed to do on a test machine, and filled up the 
filesystem up with the src tree, and just dd'd a file to fill up the 
remaining space. It appears that I can just do a `disklabel -r -e -I 
raid0` afterwards and, well, it still mounts and all the test files are 
still on the filesystem afterwards at the very least.

Is this actually safe to do though? The real RAID-1 array is just one 
large 'home' partition, but it's on two different sized disks. One's an 
80gb and the other is a 60gb. On the 80gb I made a 60gb partition for 
the RAID, and there's a 20gb partition mounted as 'spare' for the left 
over. Urgh! Stupid me...