Well that is nuts.
Grabbed the a fresh laptop, used xloader, plugged in a mini (w/power), selected the only com port available, mega2560, and it uploaded just fine. Tried it a second time, no problem, tried to change to 250000, no go.
Just have to be careful to clarify in teh instructions the firmware connects to things at 250000, the xloader uses the default 115200 no matter the firmware.
COOL!