Are there problems with using SQL Server AlwaysOn Availability Groups with Windows 2008R2? [Cross post from StackOverflow]

Brent Ozar published this webcast (slides, video with free registration) entitled "Real-Life SQL Server 2012: AlwaysOn Lessons Learned", in which he repeatedly states, with varying degrees of force, that


  using Windows 2008R2 with SQL Server 2012 Availability Groups is a bad idea


Among issues he raises are:


Quorum recalculation (a feature of Windows Failover Clustering introduced in Windows 2012)
Numerous bugs requiring Windows Hotfixes (list in AlwaysOn docs, "StackOverflow patch"), though I'm much less interested in problems that are fixed by bringing my deployment up to date.


He doesn't talk about other specifics of why using AGs with Win2008R2 is a bad idea, other than stating that AlwaysOn "pushes Windows clustering harder than any other app, and is uncovering breaking points". It is worth noting though that this is a supported configuration (AlwaysOn system requirements).

What problems have been seen in new deployments using SQL Server 2012 AlwaysOn Availability Groups with Windows Server 2008 R2, and are these eliminated by using Windows 2012? Are there problems seen in Windows 2008R2 that are fixed in Windows 2012 but do not have hotfixes available in 2008R2?
We have multiple customers using SQL Server 2012 with availability groups on Windows Server 2008 R2. The fixes listed in the pre-requisites for implementing availability groups needs to be applied for Windows to ensure that you don't run into known issues.