Hi Paul,
In this application you're effectively using it as an "isolated" patch- i.e. with XLR chassis plugs/sockets Pin 1 is connected only through the plug/socket itself and doen't actually touch the metal chassis of the patch panel (as long as the plugs/sockets you use as patch leads don't have pin 1 linked to the shell)
This is the same as plugging an XLR cord directly into the equipment and sending it to the following piece of equipment.
Providing-
a. the outputs and inputs are true balanced (either electronically or via transformers)
and
b. the equipment has proper internal Pin 1/chassis/electrical grounding layout
...you should be good to go.
One thing that helps is to have the equipment in the pre/FX rack connected to the same mains outlet as the desk/recorder via the minumum number of plugs/sockets/adaptors etc. The mains wiring should be adequately rated (to ensure a good earth connection) and use high quality signal cable.
You can also bond the metal rack chassis to mains earth using a 6mm cable to help screening and for electrical safety (this also applies to other metal outboard racks)
I find it best to keep all mic tie-lines direct without any shield/pin 1 grouping at the bay, as it ensures the phantom power return to the pre is direct.
Mark