well the way i see it is as long as Firefox patches the flaws quickly. then it should typically not matter to much. (plus until Firefox becomes 'bigger' , most flaws will probably still mostly target IE.)
i been using Firefox as my primary browser since a little prior to when it went v1.0 final and i don't think i would personally switch browsers anytime soon because Firefox is thoroughly established now and it's 'extensions' are a huge plus in it's favor, which gives it the 'overall' advantage over most other web browsers out there if even technically it's not the fastest browser.
EDIT: well after reading the article sounds like some of the flaws might be due to certain extensions etc. so it appears the thing aint totally just 'firefox itself'. either way, Firefox is still safer than IE if you ask me at the end of the day because 'Active X' is just a bad idea for Microsoft as it opens users to potential more flaws etc.