For your information. The NetApp ONTAP DSM for Windows MPIO v4.1 has been released yesterday!
I have just version 4.1 on two Hyper-V Server (Windows Server 2012 R2) and it works flawlessly. No noticable performance improvement though.
But I am not sure yet wether ALUA should be enabled on our 7-mode. Is ALUA supported and required on ONTAP 8.1 7-mode? The release says it does, but I thought I read somewhere that our setup does not support ALUA or that is does not need to be enabled.