6
The main problem is the same, users don't need the announcements :(
If we could have this information displayed on the admin page it would be great.
I also agree that when a site is running well, there is no reason for upgrading.
I have upgraded my biggest site one week ago and it was still using 2.3.2b. I did it because I could not use my recent modules and because of the anti spam protection of the new protector module. I was not really worried with security issues. Many of them are solved just by using protector, the others that are not, usually require the hacker to be logged in and to force a user to click on a malicious link, etc. I was only hacked one time and that was because I used a poor ftp program that leaked my password.
Btw,
the main problem I detected was not the upgrade to 2.5.4, but the upgrade I did on php version. Moving to php 5.3 broke some of the modules (but was easy fixed by replacing '=& new' with '= new').