[SOAPBOX] I have this same discussion on the Transformer Forums. Everyone says "You need to do
AT LEAST ONE Factory Reset when receiving an update!". I highlighted the at least one for a reason. I find it funny that they think doing multiple factory resets are needed. One will just not do

. My favorite rules for update includes Backup (good), Then Factory Reset 3 times to make sure everything is clear (ha ha), update, Factory Reset three times again (again one is not good enough), then restore your apps from your backup
I even posted what a firmware update does and what a FR does (link and all) and I am told "well users report things are much better if you do multiple factory Resets!"

. Ahhh Testimonials got to love em and take them with a grain of salt. I also like manufactured numbers or people who infer those numbers "A majority of the people on this site says it helped them" or better yet "95% of the people I have helped on this site say doing multiple Factory Resets helped them!".
GAAAAAAAHHHHHHHHHHHH!!!!!
My favorite response to all this? I did the FR and it is still having issues

. OR I did a FR and now all my data/apps are gone, how do I get everything back!
I am of the thought (based on years of experience in this industry) that Factory reset is ONLY needed as a last resort. If you are seeing some behavior on your phone that can not be explained or helped away then maybe a FR would be a good start. We all know that apps can have an impact on systems (such as battery life). But because of the sandbox methodology used by Android this limits the apps ability to interfere at the OS level unless given special permissions similar to the released Google products/apps. Even they are shielded from doing harm in some ways. [/SOAPBOX]
Sorry but I really dislike the myths running around the Android world about all this.
As with any update backup. Take the update and use the device. If the device is acting up in some manner come back here or XDA first and ask your question. If there is not a reasonable answer available then and only then do a FR.