My hunch is that 400 cigs will also be fine in future.
1. No-one overseas makes packs of 250
2. "Gee last time I came through the man said 400 was fine - when did this change?"
3. The duty collected on 150 cigs would be not worth the paperwork.
4. MOST IMPORTANT - any seized cigs CANNOT be sold at customs auctions as the specific oz health warnings are not on them, and even Govt needs to abide by those rules. The EXACT wording and size must be used or they cannot be sold.