Let’s do the sums. Transfers of 2000 FlyBuys points to Velocity would normally get you 870 Velocity points. Transferring during a 15% bonus will get you exactly 1000 points.
If you take advantage of the current promotion by shopping at one of the participating retailers (Coles, Coles online, First Choice Liquor, First Choice Liquor Market or Liquorland), you’ll end up with 970 Velocity points from each transfer of 2000 FlyBuys points.
If you shop at two retailers, you’ll end up with 1020 Velocity points, and if you shop at three, you’ll get 1070 points per 2000-point transfer.
So if you shop at more than one of the above five retailers during the promotion period, you’ll get the equivalent of more than 15% extra.
Note that, of the list of places you shop above, Coles Express and BP are not part of the promotion. So if you didn’t change your shopping habits at all, a 15% bonus is the better option for you.