Many thanks to Matthew Kerr and Kirk at ETC for helping me re-image the Ion's hard drive to update the XPe version.
One trick to know is:
If updating the console and not connected through a GCE system, unplug any other USB devices attached to the console, including fader wings.
Updating the software is (typically) a snap. Re-imaging the first console took 6+ hours (between download times, difficult USB sticks, and Ion issues). Re-imaging the second console was a snap, and took 1.5 hours, including updating the RFR.
Thanks Matt for your patience and cheery greeting each time I phoned.