Used this promo to essentially buy discounted first class in advance at approx ~1/5 of the price of retail. Not a horrible deal, assuming that the desired dates are available in sufficient quantity.
Of note, after one test purchase, the subsequent purchase (since it was for more than 1 ticket) was pending for a bit over 24 hours, leaving it a bit in limbo, as M&M said it was not possible to hold first awards.