We had the choice and chose the 318, Three things.
1. More room in the bunk house, it is much more comfortable when we had the 3 kids in it vs. the 319.
2. The pantry storage. While I can appreciate the large fridge the 319 offered, truth is, dry storage is very important for large family camping.
3. 318 was 2g's cheaper
If you can step out to a larger market to find a 318 touring edition, I would take that road. Our dealer still has a few because they ordered the most of ant dealer in the country.
My 2 cents.