To get a very clear idea (numbers are in CDN$):

For 100 units sold during the PP, Poet got $1.22/share x 100 = $122

When the attached warrants are exercised, it will get additional 1.52 x 100 = $152.

So, once exercised, Poet will end up with $274 with 200 shares dilution.

If Poet sold 100 shares using ATM during these past days, with an average of $2.74, it will get the same amount, immediately, at the expense of just 100 shares dillution.

So the result using ATM is better than half dillution, considering that the warrants do not bring immediately cash into the coffers.