Yes you should, you should always keep your browser, plugin and other software up to date, latest version are less buggy, fixed ton of crash, and fix some performance issue, so if you need best result, you should always keep your browser up to date.:)

Thank you! One more Q: 9.0 was made to satisfy )S 10-LION, and had many bugs; Patches came with 9.0.1 -- but still primerily for LION. I have 10.6.8 SNOW LEOPARD (many reasons, CS 4, etc.), and everything works with no problems at all (my Firefox 8.0.1.). Some people say "what is not broken, ..." Maybe I should just wait for a while?