If ad-block plus add-on goes to opera along with xmarks and few other FF add-ons then i have no other choice than to switch.
I don't know about passwords but for bookmarks this trick still works:
Export Firefox bookmarks as html
Import into Opera
Close Opera browser
Open Opera bookmarks.adr in a text editor
There should be a folder line underneath Trash or near the top that says
something like "Bookmarks imported from Firefox"
Delete that line and the imported bookmarks will fall into place
under the others. I usually delete the stock ones that come with a
new install. I use folders on the bookmarks toolbar so to get those I
have to drag & drop them onto the Personal Bar(if they still call it that)
but that only takes a few seconds.
All the free bookmark transfer programs I've tried I still have to go into
bookmarks.adr to get rid of that superfluous folder.
Periodically I use XMarks to sync from Chromium to Firefox but I don't leave it on all the time. Too many issues with duplicates. At least now FF has CheckPlaces and Chromium has Bookmark Sentry to get rid of the dupes.