Bigger images are much better. We show an example in the course when we train cats v dogs on larger images, and get much better results. But you’ll also find you need smaller batch sizes (since you run out of GPU RAM) and more time (since there’s more computation). So in the end you have to make your own assessment of time vs accuracy.
It would be great it some people built models using larger images. Would be a great project for a student in fact!..