This is based on when I updated my N710C to an N760C so it may not be current....
Sony's policy was that they would only support the unit with the operating system they shipped on the unit. If you upgrade yourself they will not only not support it, they will not service it. That is my understanding and I may be wrong.
Even when they had the N710C upgrade program, they would not support or service an N710C that was upgraded by anyone other than their service center. That seems a bit harsh on the surface but technical support is a very expensive aspect of a manfacturers budget and fixing someone elses screw ups, especially where upgrading operating systems is concerned, can be very time consuming and expensive.
By the way, I believe this policy also applies to Sony's PCs. If you buy a Sony PC and upgrade the OS, they will not support it or service it unless you take it back to the original OS.