Thanks for the heads up, I vaguely remember reading that awhile back but was miffed that Firefox was forcing you to choose it's service only and not provide another external secure source method (https, webdav, sftp, etc.) to a location of your choosing.
Just miss not being able to sync my own data to my own device (pogoplug, or my own web server).
I hope the external sync devs will someday start making compatible extensions again.