I agree with Biscuit Chucker. I enforce hand luggage limits at boarding but if the bag doesn't fit into the unit because of wheels are it is *slightly* over packed then I let it through after drawing the pax's attention to the fact. However I am very strict about weight. I had a bag fall onto this lap infant once and it wasn't pretty! Also I a pax has an international size wheel aboard and a *very* small item (like a thin laptop bag) I will usually let it slide.
One thing I will never do is agrue with pax. The rules are there for a reaosn and I deny boarding until they part with their bag. I have never seen a FA win an agruement with pax about hand luggage. Simple - just don't argue!
In the past year at Impulse we have seen a kitten and some ducklings onboard! Crazy but true! Qantas has to stop advertising on shop-a-dockets! What do you think, Biscuit?