They've always seemed terrible to me for speed and thermodynamics reasons (it's so much easier and faster to move an electron than a bunch of neutrons). I suppose from a computational perspective you could do a simple, or set of simple computations in a machine more resistant to, or at least more resilient against, EMP (as the thing that is easy to move in a B field, that electron I mentioned above) is easier to move in undesired wave when subject to a large external B field. I doubt it though.
However you do raise the possibility of longer-lasting computers in other harsh environments, specifically space. The Voyager probes work in part because the feature size of the components is huge (discrete transistors that are inspectable through a microscope and in some cases the naked eye). Such components are hard to come by these days. Micro mechanical devices might even be a superior approach. And for most space applications speed is not critical.
I don't think that you'd ever want to literally have sliding mechanics. However, the dual rail logic used is a type of reversible computation. Thus, thermodynamically it is theoretically much more efficient than standard (irreversible) computation because bits are never erased (which accounts for most of the energy loss).
However you do raise the possibility of longer-lasting computers in other harsh environments, specifically space. The Voyager probes work in part because the feature size of the components is huge (discrete transistors that are inspectable through a microscope and in some cases the naked eye). Such components are hard to come by these days. Micro mechanical devices might even be a superior approach. And for most space applications speed is not critical.