Rated 3 out of 5 stars
Don't put your perma-tabbed pages at the left of the tab bar. Perma-Tab apparently just counts to get the tab location rather than know what the content is. E.g., if an add-on is updated when you start Firefox it often opens its home page or info page at the extreme left. This will replace the content of the Perma-Tab that was there and push all else to the right, requiring you to un-Perma-Tab that tab and start over. Frustrating.