Great! Thx for your answer spuluka. Although it sounds not like a practical solution to me. It's just too complicated for hosting a simple testsystem. I thought it would be great to have a mirrored test network, where everything can be tested like in the real production environment. Especially upgrades of vsphere hosts and vcenter appliances.
Is it just an issue of ScreenOS that this scenario is so complicated? Or is it just not a good practice to design a test network like this?