I am considering buying Garmin Montana 650. I now have a Etrex 30 and have downloaded many maps from this site and unlocked them with the tools found here ( I usually use fast img unlocker v2.1). All have worked without problems. I now read that the latest firmware updates to the Montana 600 series have a Map authentication process which may give problems. Anyone have any experience with this unit using this kind of unlocker?