I was using my Bold with .247 and this morning I upgraded to .266. I have one problem so far and that is when I remove the an email from my BB 9000 the new version does not give the option if I wish to remove it from the handset or the mailbox. I had that option with version .247.
I tried couple of set up in the email setup options but I was not able to find a solution for it.
Should have stayed on 247 imo. 266 has an issue where the phone reboots if you skip ahead or back too much in a media file. Especially awful if you use podtrapper.
Other than this I have not noticed much difference between the two but that problem alone was enough for me to downgrade.
Posted from my CrackBerry at wapforums.crackberry.com