We seem to be going around in circle's here (as we usually do). To answer the original poster's question I would like to point out two things.

1. Money is money. It doesn't really matter which column it shows up in on your paycheck. What really matters is the amount that you put in your bank account.

2. It seems your trying to figure out whether overnights are offset by the increase in cash. I would say that you shouldn't choose primarily on per diem or not, but it should be a factor in your decision process. If you like less commuting and live far away from your base, overnights are an excellent choice to maximize working time and the per diem is a bonus. Keep in mind that its not a huge amount of money, but just enough to offset living expenses while on the road.

I hope this helps, and good luck to you.