Some positive experiences, to broaden the baseline...
I have had almost no problems updating my old 568, my current 568.2 or my 562v.2.
I am using a Toshiba laptop running Windows98 (not SE) and use the Meridian supplied serial cable. It doesn't matter if the devices are on or off when I plug in the cable or when I start the config package: it just works.

Regards,
Mark