Yeah. This $.1 is only one instance. You ppl read patch notes?
1st their internal wow is way more advance then ptr and when migrate to real server create problems that did not happen on ptr so they have ti fix it fast.
2nd 4.1 is way more extend then 4.2. If what I know is right 4.2 will be Firelands and some late fixes to 4.1 (probably tooltips). This one introduce way more features and changes.
Patch are not about instance only go check what they introduce and see for yourself.
A instance and raids are only graphics with some scripts on bosses nothing hard when you compare with new lag system, graphics, classes changes, guild and queue changes, etc...
And btw not all server did the extend. Some are allready up.