Hey Ben,
I got this error "The WinRM client cannot process the request. It cannot determine the content type of the HTTP response from the destination computer. The content type is absent or invalid."
and eventually traced it back to a missing globalModules entry. Here's a suggested revision to step 2 that includes making sure kerbauth module entry exists too.
2. If the WSMan -or kerbauth- module entry is missing from the global modules section of the C:WindowsSystem32InetsrvconfigApplicationHost.config file, as follows:
<globalModules>
<add name="WSMan" image="C:Windowssystem32wsmsvc.dll" />
-- <add name="kerbauth" image="D:Program FilesMicrosoftExchange ServerV14Binkerbauth.dll" /> --