Masterpassword used to be my plug in of choice in this category, until it failed for some reason.
The developers website homepage does not have anything but a email address listed and those that use Virtuemart may be disapointed as it also disables the VM Breadcrumbs.
But if it works for you, let us know!
The SEF problem you describe is not related to this module; just tested it and with SEF on or off there's no difference, it still works.
What happens if you place BreadCrumbs Advanced in another moduel-position (e.g. bottom)?
Our webpage is under construction but for support the email address should be enough, isn't it?
We haven't detected the Virtuemart problem and suprises us; BreadCrumbs Advanced is an adjusted (original) source from the Joomla! 1.5 BreadCrumbs module.
Perhaps you're using the default breadcrumbs position instead of a seperate breadcrumbs_advanced position in your template.