Hi!
As long as you have the SIT tone and the no service message too I do not think it can hurt...
The SIT tone is not supposed to be used alone so using it alone would not be enough...
Playing only the no service message would not be enough either because a lot of people the world over know that the SIT tone indicates a problem even if they don't understand the no service message because they don't speak the language...
Is it too much?
Hey, as mail server admins say, your server, your rules... It's up to you to decide what you are happy with..
In my case I wanted the no service message to be in the two official languages of my country so I still have custom code to handle this...
Have a nice day!
Nick