Updating M1KPNAV attached through M1DBHR

Just getting around to updating firmware for my M1 system elements, and for the M1KPNAV there is a warning that reads:
 
Firmware flashing of a M1KPNAV is not possible while it is connected to the M1 Control through a M1DBHR Data Bus Hub Retrofit
 
 
 
Is this a new issue?  I have updated my M1KPNAVS several time before, and they are all connected via M1DBHR.  
 
It will be pretty challenging to rewire the NAVS just to update them.  Of course can be done, but would rather avoid this.
 
Any information on why this warning, and the dangers of not heeding it?
 
  tenholde

Flashing firmware is usually a process that is sensitive to precise timing.  I'll speculate that the M1DBHR alters the timing of the data bus enough so that it may not always be within the specs required for flashing the firmware.   It may work, or may not.  The result might be that you end up with a bricked KPNAV. 

Has anyone tried this?