Is Hyper-V under ESXi stable and effective to HW performace? I want to have primary Windows Server 2012 with services in Hyper-V like Exchange, and other OS under ESXi like Linux. Is this good way or is better clean Hyper-V on Windows Server? Or ESXi with more than one Windows Server under ESXi instead of Hyper-V?
It would certainly be better to either use Hyper-V or ESXi, but not one on top of the other. It would slow down the system, and on top of that is not necessary. Which one to use out of Hyper-V and ESXi on the other hand is a completely different question and depends on what you will be using the virtual servers for.