vSphere Client 5.5 Update 2
One of the nice change in the vSphere 5.5 Update 2 release from yesterday, was the updates to the vSphere Client (c#).
With this update i is now possible to Edit Virtual Machine using Compatibility Mode 5.5 (former Hardware Level 10), stil with the limit to the Compatibility Level 5.0 (Hardware Level 8) features.
The old one had the problem that if you had youre vCenter running Compatibility Level 5.5, and you need to do som changes to this Machine will the vCenter Machine was Power off, your only choice was to edit the VMX-file or do it thru PowerCLI.
Another case is when using the Free VMware Hypervisor, and accidental upgraded the Compatibility Level, and ignoring the warning.