The operative word in my post (#7) was require, maybe I should have made it bold. I have no problem either way, it's the crew's call.
The only time I've had emergency services on standby in a multi was after an unscheduled auto-feather in a DH8 ex Broome.
Having called them out for various reasons, we circled Broome airfield for what seemed an eternity (about 30+ mins as I recall) before they were in position, whereas we could have landed fairly soon after the event.
In hind sight, I believe that in that instance I would have been better off not asking for them as I had no reason to believe that the landing would be anything other than normal. If placed in a similar position tomorrow, I wouldn't be asking for, or waiting for emergency services.