Just to add my datapoint...
Downloaded and updated to Build 2.11.605.9 smoothly. Seems fine, but I guess time will tell. I'm optimistic that the new radios will be even better. Although, I was very happy with mine before the update. Just FYI, the new radios are 1.48.00.0930w_3 (CDMA) and 0.01.78.0916w_3 (LTE).
Details..
When I checked for updates I was getting "No updates avail" most of the day. Then, around 2pm Denver time I got "update available" and proceeded to OK and continued. This time was comserate with a number of other folks who posted about that time that it just became available.
During my first attempt, after what seemed like the whole download took place (I didn't have the download progress bar on the screen so I didn't know for sure), I got a "Server Error" message. Heck, I was literally sitting right under a good 4G antenna too. Then, I tried often for the next 4 or 5 hours and kept getting "No updates available". My update status screen said "Update Failed". I tried this both before and after various restart/bat-pulls.
So... I went into application management/all and found an "Updater" application, whatever that is

. I had a choice to Clear Data or Force Close. I was afraid to Clear
data because I didn't know what this app really was anyway, so I just did a Force Close. I figured, at least that way it would start again after a reboot. Well, then I tried to update the software again -- got a hit! This time I got the "update available" message and selected OK and all went smooth after that.
So, if you keep getting "No update available", try Force Closing the "Updater" application (whatever that is

).
-Frank