I don't know what "better off" means to you...
The prebate makes necessity level spending tax free.
From your comment, you feel that giving poor people more money in refunds than they pay is a good thing.
That's very curious. Just a few posts back you were deriding the nrst for providing tax refunds above the amount of tax paid.
Are you rejecting the nrst because you believe it overpays tax refunds to poor people
or
Are you rejecting the nrst because it doesn't overpay tax refunds as much as the income tax?
You should stop digging!
The size of the prebate has nothing to do with taxes paid, goods and services purchased, or income earned. It is determined by family size, and that, alone.
Further, your claim that people below the poverty level spend up to and exceeding the poverty level is somewhat misleading because "spend" in the sense you are using the word includes charitable gifts to the family as income spent. As I understand it, taxes are not paid either by the charity or the family. I'm not suggesting that's wrong, just noting what is. Sometimes that's called telling the truth.
For those reasons, the prebate is not a refund of taxes paid, or about to be paid. It is a grant, or entitlement, as FairTaxers say, to be spent or saved, or to do anything one wishes to do with it.