Cheers. I'm currently taking the painful approach of rather than importing lightroom catalogs and images in their current messy format, I'm trying to sort out my workflow and reorganise things a bit. Only got 15k pics to move around but the trick is creating a structure that I won't outgrow in a while.
I'm going for the RAW on NAS with catalogs and JPG exports local to the Mac. Then a separate NAS share with backups of everything local. Mac is mirrored, NAS is mirrored so that should be enough copies of everything! lol.