The vSphere Client (aka C# or thick client) 5.5 Update 2 now supports the ability to edit a virtual machine using virtual Hardware 10.
Using this version (build number 2001466 and higher) you can edit hardware version 9 and 10 VMs, but only with the feature level of hardware version 8.
If you use an older version of the vSphere Client and try to edit an VM with HW Version 10 you will get the following error:
You cannot use the vSphere client to edit the settings of virtual machines of version 10 or higher. Use the vSphere Web Client to edit the settings of this virtual machine.
I wrote an blog article about this problem in combination with the free vSphere Hypervisor 5.5 some month ago: The vSphere Hypervisor 5.5-Web Client-HW Version 10-dilemma
With the new vSphere Client 5.5 U2 you can now edit the following properties:
- increase RAM
- decrease RAM
- change network port group
- remove devices
- increase vCPU
- decrease vCPU
- mount ISO
- increase disk space
- set a limit
- remove a limit
- set a reservation
- remove a reservation
- edit advanced settings
You can read more about this topic in VMware KB 2061336:
Editing virtual machine settings fails with the error: You cannot use the vSphere client to edit the settings of virtual machines of version 10 or higher (2061336)