Folks are so conditioned to using Get-Member to discover properties and methods on types that it is a bit unnerving to not find methods on CIM instances with Get-Member. It is also unintuitive IMO to have to use this:
Get-CimClass Win32_Process | % CimClassMethods
... to find CIM methods when Get-Member will happily show CIM properties. It would be nice to have Get-Member recognize CIM instances and display CIM methods perhaps with a special notion (CimMethod) so we know that we have to use Invoke-CimMethod to invoke that particular method. Another option is to add a new Get-CimMember cmdlet that is the CIM oriented equivalent of Get-Member.