Firefox 4 -- to upgrade or not to upgrade?

     Wow is the new Firefox fast! Boy, do I wish I would have checked the compatibility of my add-ons/extensions before I upgraded!

For example, I found out that the following applications that were not compatible:

     I was really bummed because I use some of the extensions, like LinkDiagnosis and Mozbar, quite extensively.  I felt like I needed to go back to version 3.6.  Apparently, a few other people felt this way as well: http://support.mozilla.com/en-US/questions/795075?s=go+back+to+previous+version&as=s

     Here’s how I was able to "roll back" to 3.6 (big thank you to "TonyE" for his post on the above forum :

     “I strongly advise against going back to Firefox 3.5, when you installed Firefox 4 it made changes to a couple of files that store user data, those files will no longer work in Firefox 3.5. If you go back to Firefox 3.5 the files containing bookmarks, history and cookies will be lost, causing you to lose all history and cookies, with bookmarks being restored from a backup.
If you want to downgrade it would be better going to Firefox 3.6.15.
To downgrade to Firefox 3.6.* you can uninstall Firefox 4, but do not select the option to "Remove my Firefox personal data". If you select that option it will delete your bookmarks, passwords and other user data.
You can then install Firefox 3.6.* available from http://www.mozilla.com - it will automatically use your current bookmarks, passwords etc.
To avoid possible problems with downgrading, I recommend going to your profile folder and deleting the following files if they exist - extensions.cache, extensions.rdf, extensions.ini, extensions.sqlite and localstore.rdf. Deleting these files will force Firefox to rebuild the list of installed extensions, checking their compatibility, and reset toolbar customizations.
For details of how to find your profile folder see https://support.mozilla.com/kb/Profiles “

Thanks to "mlwalker" in the same thread, I was able to find the download page for version 3.6:
http://www.oldapps.com/firefox.php?old_firefox=109
    
     Finally, after the reinstall of 3.6 I did have to reinstall HTML Validator, but by the time I was finishing this post I noticed that the LinkDiagnosis tool was upgraded to work with Firefox 4!  I haven’t tried it yet since I’m waiting for updates to the other tools I use.  Hmm, I wonder if the greater speed I initially experienced might have been due to fewer extensions being loaded?  Guess I’ll have to wait a little bit to find out.