Have a look at the latest attempt at consultation - I've never seen a survey like it. Removing it completely for those not in receipt is one option as is increasing the parental contribution (tantamount to the same thing I believe).
It's worth a look even if you don't complete it, but only available on the Intranet.
What surprised me was the way the Questions were asked, in the form of "indicate on a sliding scale whether you would rather pay £1000 more or have the allowance withdrawn for those not already in receipt."
Of course paying more for it simply changes it from an all ranks alllowance to one which is available only for wg cdrs/gp capts and above.