I think you two are looking at this from a slightly different perspective.
If you wire so that both down = off, then clearly as soon as you move one switch up you will be left with the situation where the other switch being down will result in the light being on.
But however many times you operate the switches, these conditions will hold true:
1. Both switches down = Off
2. Both switches up = Off
3. One switch up, one switch down = On.
Swap the travelers over at one end only and these three conditions will always hold true:
1. Both switches down = On
2. Both switches up = On
3. One switch down, one switch up = Off
