really, the problem with adjustable cables is not the construction so much, as it is the extra length. the adjustable cables are a good couple inches longer or so. This extra length makes it impossible to route with creating a sharper bend. This sharper bend created from the extra length causes more cable effort, binding and snapping.
I run an adjustable cable, but on my 66 mustang, and it's routed perfectly and i've had 0 issues with the adjustable cables.
as well, some people spend a buttload of cash on the oem cables. I've used the $20 autozone stock non adjustable cable more than once. It's always held up, AND has a lifetime warranty