I currently use about 22 Firefox Extensions/Addons.
12 of them are not yet and may never be compatible with Firefox 5 which is more of nice to have rather than security enhancement update to Firefox. All the 22 Firefox Extensions that I am running that are compatible with Firefox 5 are interestingly enough also compatible with Firefox 6.
Right now I am planning to skip Firefox 5 and wait for Firefox 6. This could change depending on what happens with the Firefox Extensions/Addons that I use that at this time not compatible with Firefox 5.
WebRep should be the last reason for deciding on whether to update to Firefox 5. WOT is compatible with Firefox 5 and 6. People here don’t think much of WOT compared to WebRep. However if you go to the Avast forum hated IObit website you will see that WOT shows it as yellow whereas WebRep shows it as solid green. ???