Exempt But sent a questionnaire? IB113

I have read the IB113 questionnaire guide and on page 7 there is this sentence, at the end of one of the letters to send.

If you do send this letter, make sure you get proof of postage and do let us know what response you get because, at the time of writing, this is an untried tactic.

So my question is, has anyone sent the letters off and what was the response, i have looked through the forum but could not find anyone whom had used this tactic(if that is the right word).
I am not at this stage yet, well none of the stages but forewarned is forearmed!