The main difference between various models of the same manufacture, of say road bikes, lies in the quality of the parts. Poor quality will have very wide tolerance giving lots of slop, and in general won't last very long or stay adjusted long. If you buy a Wally Mart bike, that is what you get. In ignorance people will wonder why bikes at bike shops are so expensive compared to such klunkers. It is a pleasure to use / ride something of good quality compared to klunkers.

The same may not be true of folding bikes unfortunately. The majority of what is offered for sale is the cheap and nasty stuff asked at the mass market so only have $1.30 to spend and won't ride it much at all. For you who want to travel from Nepal to the Congo, I would spend some of my money on established quality bike such as Bike Friday. These use widely available parts you could source from almost anywhere in the world.

You mentioned spokes? If you choose a Wally bike, expect lots of spoke breakages. Too low tension, rubbish fatigue life.

Of course, you *can* ride between Nepal and Congo on a Wally bike. It may even never break. You probably don't have to worry about theft too much, although in Africa, anything that isn't made of dirt is worth stealing. So not much comfort from a cheapie there. Might as well get some enjoyment out of a quality bike along the way.