I have been using 700 with 35mm wide tires. I have done 1200km in Mexico and 1700km (and counting) in India. I have 700s because that is what my bike needed and I wasn't going to buy a new bike. Would I buy a bike that didn't fit because I was forced to use 26in? No. I haven't busted spoke, or warped my rim, then again I spent the cash to have really good rims, spokes and hubs. I'm not afraid to go off road or exploring, with a loaded bike you won't be getting air, or jumping curbs.

Mind you, it would sure be a bummer if you broke your wheel in the middle of nowhere and had to catch a ride somewhere to get a wheel (if it is possible in that country). Keep in mind that you won't be able to find a lot of things in a third world country (like an axle, or disc brakes). You can spend the money and hope it holds up to their name (which is what I do) or you could get a single speed, be like the locals and know that you can buy the exact same bike if it breaks. I think most people are somewhere in the middle.