There's a lot of variability in the type of flying you can get assigned to. If you have a weird sense of humor and you're pretty mellow, you'll be fine. I'm including non DoD/DoS work into this, too.
Whether you carry a gun or not doesn't really matter unless you've got to do some of the weirder stuff. Weirder stuff would include going to a bank to get a sack of cash or otherwise exposing yourself to petty crime.
I guess I'm trying to say it doesn't really matter whether or not you're sent out to fly with a gun. There's more important stuff to consider.
Knowing what I know now, I'd advise guys to look at this:
If the company changes policies on you after you get into the country, are you going to be stuck? If the ******************** hits the fan, can you airline back out? Can you do this without using any of the company assets (drivers, contacts, etc.)?
Consider your transportation and housing. Til you get a month or two in-country, you're going to be living in the compound or other safe spot that you have. Life will be similar to that experienced on an aircraft carrier (luxury aircraft carrier?). If things are going to get under your skin over a week or two, you'll be crawling up the walls in month or two.
Where are your paychecks coming from, and is there anyone who goes to jail if you don't get the pay you're promised? (This won't be a likely factor with DoD or DoS stuff.) If pay isn't directly deposited into your US or EU bank accounts, can you get your cash out of the country? What banking and financial limitations and capabilities exist with regard to your potential assignment?
Evaluate the amount of support your potential employer gives its crews in the field. Compare what they tell you to what you hear from crews, handlers, etc. If there's a big split between what's advertised and what's delivered, be ready for a surprise. How do they plan on getting important parts to the base? How do they plan on taking care of maintenance? Is this realistic? How will parts move from the DHL airliner to your particular airplane? Will you have to hire a trusted local to escort your deliveries past certain authorities/agents?
Look at any other pertinent logistic and political concern regarding the assignment. You'll find that the DoD stuff based out of US military facilities is pretty chill compared to guys flying Dash-7s in Liberia.
If you do finally decide to go, know that you're going to get some nasty and some pleasant surprises. Roll with it, man, and try not to get sick. You'll have a really cool time, if you're whacked like me.