This is a great idea, I was thinking about suggesting this, but it would seem that you beat me to it.
There is however a problem with what you expect the helpers to post when welcoming new members.
When a member posts an introduction thread, it wouldn't feel very welcoming to the member if the first response is a generic pre-written response. You want to give new members the best welcome you can give, I believe every response should be typed, rather than copy and pasted, but still contain the same info.