When deploying the App-V Client at a customer site the installation failed (or halted was more like it). It seems that a few parameters caused issues and once reviewing the log-file it became apparent which. Last part of the log-file looked like this;
MSI (s) (68:78) Executing op: CustomActionSchedule(Action=OptIntoMu,ActionType=3073,Source=BinaryData,Target=AppvPerformMUOptInInstall,)
MSI (s) (68:B4) Invoking remote custom action. DLL: C:\Windows\Installer\MSI37CC.tmp, Entrypoint: AppvPerformMUOptInInstall
Fault injection has been disabled by policy.
The parameters set during the install (for App-V 5.0 SP1) was set like this;
/ACCEPTEULA=1 /ENABLEPACKAGESCRIPTS=1 /MUOPTIN=1 /CEIPOPTIN=1 /NORESTART /q
Toggling MUOPTIN to 0 resolved the issue – which is great. I am guessing that if updates are provided through Microsoft Update they will simply have to be deployed through normal software distribution.